Parallel evolution of senescence in annual fishes in response to extrinsic mortality
Terzibasi Tozzini E, Dorn A, Ng¿oma E, Pola¿ik M, Bla¿ek R, Reichwald K, Petzold A, Watters B, Reichard M, Cellerino A
BMC Evolutionary Biology 2013, (3 April 2013)
Early evolutionary theories of aging predict that populations which experience low extrinsic mortality evolve a retarded onset of senescence. Experimental support for this theory in vertebrates is scarce, in part for the difficulty of quantifying extrinsic mortality and its condition- and density-dependent components that –when considered- can lead to predictions markedly different to those of the „classical“ theories. Here, we study annual fish of the genus Nothobranchius whose maximum lifespan is dictated by the duration of the water bodies they inhabit. Different populations of annual fish do not experience different strengths of extrinsic mortality throughout their life span, but are subject to differential timing (and predictability) of a sudden habitat cessation. In this respect, our study allows testing how aging evolves in natural environments when populations vary in the prospect of survival, but condition-dependent survival has a limited effect. We use 10 Nothobranchius populations from seasonal pools that differ in their duration to test how this parameter affects longevity and aging in two independent clades of these annual fishes.
We found that replicated populations from a dry region showed markedly shorter captive lifespan than populations from a humid region. Shorter lifespan correlated with accelerated accumulation of lipofuscin (an established age marker) in both clades. Analysis of wild individuals confirmed that fish from drier habitats accumulate lipofuscin faster also under natural conditions. This indicates faster physiological deterioration in shorter-lived populations.
Our data provide a strong quantitative example of how extrinsic mortality can shape evolution of senescence in a vertebrate clade. Nothobranchius is emerging as a genomic model species. The characterization of pairs of closely related species with different longevities should provide a powerful paradigm for the identification of genetic variations responsible for evolution of senescence in natural populations.
Drew J, Philipp C, Westneat MW (2013) Shark Tooth Weapons from the 19th Century Reflect Shifting Baselines in Central Pacific Predator Assemblies. PLoS ONE 8(4): e59855. doi:10.1371/journal.pone.0059855
The reefs surrounding the Gilbert Islands (Republic of Kiribati, Central Pacific), like many throughout the world, have undergone a period of rapid and intensive environmental perturbation over the past 100 years. A byproduct of this perturbation has been a reduction of the number of shark species present in their waters, even though sharks play an important in the economy and culture of the Gilbertese. Here we examine how shark communities changed over time periods that predate the written record in order to understand the magnitude of ecosystem changes in the Central Pacific. Using a novel data source, the shark tooth weapons of the Gilbertese Islanders housed in natural history museums, we show that two species of shark, the Spot-tail (Carcharhinus sorrah) and the Dusky (C. obscurus), were present in the islands during the last half of the 19th century but not reported in any historical literature or contemporary ichthyological surveys of the region. Given the importance of these species to the ecology of the Gilbert Island reefs and to the culture of the Gilbertese people, documenting these shifts in baseline fauna represents an important step toward restoring the vivid splendor of both ecological and cultural diversity.
Pedro, S., Caçador, I., Quintella, B. R., Lança, M. J. and Almeida, P. R. (2013), Trace element accumulation in anadromous sea lamprey spawners. Ecology of Freshwater Fish. doi: 10.1111/eff.12052
The sea lamprey, Petromyzon marinus, is an anadromous cyclostome that occurs in the main Western Europe river basins draining to the Atlantic Ocean and considered a gastronomic delicacy in Portugal, Spain and France. The contamination profile of this species is fairly unknown as far as trace metals are concerned, with only a few studies dedicated to the subject. Trace elements concentration was analysed in muscle and liver samples of adult specimens from eight Portuguese river basins. This study aimed: (i) to assess the profile of essential and nonessential elements accumulation in the muscle and liver of sea lamprey spawners; (ii) to investigate possible differences in the trace element accumulation in adult sea lampreys entering Portuguese river basins; and (iii) to determine the safety of sea lamprey for human consumption regarding elements content. Females accumulated higher levels of elements than males, but only differences in the liver were significant. In a general overview, the accumulation of most elements analysed was low, except for Hg in the muscle, which exceeded the statutory limits for fish concentration. The muscle accumulation profile based on nonessential elements (As, Cd and Hg) evidenced a segregation of the samples into two groups, mostly based on Hg concentration. Distinct trophic levels and contamination of preys and differential duration of the parasitic period may be in the origin of this separation.
Martinez, P. A., Marti, D. A., Molina, W. F., Bidau, C. J. (2013), Bergmann’s rule across the equator: a case study in Cerdocyon thous (Canidae). Journal of Animal Ecology. doi: 10.1111/1365-2656.12076
1. The variation in cranial size of the crab-eating fox Cerdocyon thous was analysed in relation to latitude and several environmental variables throughout its distribution in South America.
2. We tested the existence of clines to determine whether this canid follows Bergmann’s rule to the north and south of the Equator. Also, using niche modelling, we analysed whether the climatic changes during the last glaciation could have influenced Bergmann’s rule in this species. We quantified the size of the cranium of C. thous (n = 300). The data were divided into two groups: (i) south of the Equator (n = 163) and (ii) north of the Equator (n = 137). We performed correlations, OLS regressions and simultaneous autoregressions to analyse the relationship between the variation in size and different geographic and environmental variables. Data of occurrence (n = 594) together with ambient variables from the present and the last glacial maximum (LGM) were used to predict the occurrence of C. thous with the implementation of the maximum entropy method. Present-day and historical distribution maps were obtained.
3. The variation in the size of the cranium of C. thous showed two trends. In the south of Equator, we observed that the size of the skull shows an inverse relationship with temperature-related variables and a positive one with precipitation, while in north of the Equator, we observed the opposite relationship. Populations south of the Equator follow Bergmann’s rule showing increasing size with increasing latitude. To the north of the Equator, a non-Bergmannian pattern occurs because size decreases with increasing latitude.
4. Niche modelling showed two present-day groupings in South America, one north of Amazonia and the other south. However, for the period of the LGM, four groups emerged, possibly related to the four subspecies presently described for C. thous. Therefore, it is possible that the observed pattern – southern populations following Bergmann’s rule while northern populations reflecting the opposite – has been influenced by the events that occurred during the LGM that could have led to the differentiation of populations.
Kitano, M. and Shiraki, S. (2013), Estimation of bird fatalities at wind farms with complex topography and vegetation in Hokkaido, Japan. Wildlife Society Bulletin, 37: 41–48. doi: 10.1002/wsb.255
Worldwide expansion in wind-energy generation has raised concerns about bird collisions—in particular, protected species. Bird collision studies are common in Europe and USA, but none had been done in Japan to date. We studied bird fatalities at 42 turbines (52.8 MW) in Tomamae, northern Hokkaido, Japan. For 17 months from July 2007 to November 2008, we performed 24 fatality surveys at an average 21-day interval and ≤100 m from the wind turbines. We found 52 fatalities, including 4 white-tailed eagles (Haliaeetus albicilla). Our estimate of the adjusted annual mortality at Tomamae, which used a modified equation to factor in the complex topography and dense vegetation spread generically over Japan, was 2.20 bird fatalities/MW/year and 0.36 raptor fatalities/MW/year. Bird utilization rates explained most of the variation in fatality rates among species and among locations. The highest fatality rates occurred at the turbines on a costal cliff where the rotor zones of wind turbines overlapped the frequent flight paths of large birds. The development of generalized models can be useful for predicting the impacts of other wind projects on birds, with the exceptions of high-risk situations. However, more surveys of fatality rates and utilization rates are required at this and additional study sites, and over a longer period with shorter search intervals, to develop predictive models of bird collisions with general applicability.
J.M. Baetens, S. Van Nieuland, I.S. Pauwels, B. De Baets, A.M. Mouton, P.L.M. Goethals, An individual-based model for the migration of pike (Esox lucius) in the river Yser, Belgium, Ecological Modelling, Volume 258, 10 June 2013, Pages 40-52, ISSN 0304-3800, 10.1016/j.ecolmodel.2013.02.030.
For many decades, pike populations in Belgium have been suffering from a decline of the environmental quality due to habitat deterioration, water pollution and many other degrading phenomena. Since past attempts to rehabilitate the pike populations had only limited success, it is of importance to gain insight into the spatio-temporal dynamics of pike such that more effective restoration programs can be effectuated in the future. Ideally, this can be accomplished by relying on telemetry data, but since the collection of such data is both labour-intensive and costly, researchers often resort to a simulation-based approach, which on its turn requires a sound spatio-temporal model. Therefore, and as a first step towards an integrated individual-based model (IBM) for describing pike dynamics in rivers, an IBM mimicking the movement of pike in the river Yser, Belgium, is proposed in this paper. This model considers the specificities of pike, such as its seasonally dependent migration, swimming speed and habitat preference, and is based upon environmental data from the river Yser. It is shown that the in silico spatio-temporal dynamics coincides with the one that is typically inferred from in situ observations. Amongst other things, the proposed model may be relied upon to identify the most appropriate management and restoration measures through a scenario analysis.
J.H.F. Prado, E.R. Secchi, P.G. Kinas, Mark-recapture of the endangered franciscana dolphin (Pontoporia blainvillei) killed in gillnet fisheries to estimate past bycatch from time series of stranded carcasses in southern Brazil, Ecological Indicators, Volume 32, September 2013, Pages 35-41, ISSN 1470-160X, 10.1016/j.ecolind.2013.03.005.
Incidental fishery mortality estimates of franciscana based on stranding data are biased downwards, as only a fraction of the total bycatch ends up ashore. We estimated the probability of a franciscana incidentally killed by the coastal gillnet fisheries in southern Brazil to wash ashore and used this as a correction factor to back-calculate fishing related mortality from a dataset of carcasses collected between 1979 and 1998. From November 2005 to January 2009, 145 franciscanas incidentally killed in nets were tagged and returned to the sea. Only 11 of the tagged animals were found during beach surveys. Generalized Linear Models were used to model the probability of a tagged franciscana reaching the shore as a function of the covariates wave period, wind direction and intensity, distance from coast and the target species of the fishery. The target species had a significant effect on the stranding probability. The stranding probability of a tagged franciscana was higher in the fishery targeting white croaker (Micropogonias furnieri) (median = 0.105; 95% CI = 0.05–0.18) rather than weakfish (Cynoscion guatucupa) (0.013; 0.0003–0.069). As the stranding probability estimate for weakfish was imprecise (wide credible interval) we decided to hind cast the number of franciscanas incidentally killed for white croaker season only. The corrected estimate of franciscana mortality was approximately 10 times higher than previous estimates based solely on stranding data. Finally, this novel mark-recapture approach provides a useful correction factor to reduce the bias in incidental mortality estimates derived from stranding data.
Person, E., Bieri, M., Peter, A. and Schleiss, A. J. (2013), Mitigation measures for fish habitat improvement in Alpine rivers affected by hydropower operations. Ecohydrol.. doi: 10.1002/eco.1380
In mountainous areas, high-head-storage hydropower plants produce peak load energy. The resulting unsteady water release to rivers, called hydropeaking, alters the natural flow regime. Mitigating the adverse impacts of hydropeaking on aquatic ecosystems has become a crucial step in recent water policies.
We developed a novel economic-ecological diagnostic and intervention method to assess hydropeaking mitigation measures for fish habitat improvement. This method was applied to an Alpine river downstream of a complex storage hydropower scheme. The approach comprises (1) a hydropower operation model of flow regime generation and cost estimates for different mitigation measures, (2) a two-dimensional hydrodynamic model to simulate the flow conditions in representative river reaches and (3) a dynamic fish habitat simulation tool to assess the sub-daily changes in habitat conditions of three brown trout (Salmo trutta fario) life stages (adult, spawning and young-of-the-year). Simulations showed that operational measures such as limiting maximum turbine discharge, increasing residual flow and limiting drawdown range incur high costs in relation to their ecological effectiveness. Compensation basins and powerhouse outflow deviation achieved the best cost–benefit ratio. Hydropeaking impact was strongly dependent on river morphology. Monotonous river reaches exhibited low habitat suitability for peak discharge, whereas a braided morphology provided high in-stream structure and thus suitable habitat for unsteady flow conditions.
The interdisciplinary approach to economic and habitat rating informs decision makers regarding the effectiveness of measures implemented to mitigate the environmental impacts associated with fluctuating hydropower operations.
Stuckas H, Gemel R, Fritz U (2013) One Extinct Turtle Species Less: Pelusios seychellensis Is Not Extinct, It Never Existed. PLoS ONE 8(4): e57116. doi:10.1371/journal.pone.0057116
Pelusios seychellensis is thought to be a freshwater turtle species endemic to the island of Mahé, Seychelles. There are only three museum specimens from the late 19th century known. The species has been never found again, despite intensive searches on Mahé. Therefore, P. seychellensis has been declared as “Extinct” by the IUCN and is the sole putatively extinct freshwater turtle species. Using DNA sequences of three mitochondrial genes of the historical type specimen and phylogenetic analyses including all other species of the genus, we provide evidence that the description of P. seychellensis was erroneously based on a widely distributed West African species, P. castaneus. Consequently, we synonymize the two species and delete P. seychellensis from the list of extinct chelonian species and from the faunal list of the Seychelles.
Wallner B, Vogl C, Shukla P, Burgstaller JP, Druml T, et al. (2013) Identification of Genetic Variation on the Horse Y Chromosome and the Tracing of Male Founder Lineages in Modern Breeds. PLoS ONE 8(4): e60015. doi:10.1371/journal.pone.0060015
The paternally inherited Y chromosome displays the population genetic history of males. While modern domestic horses (Equus caballus) exhibit abundant diversity within maternally inherited mitochondrial DNA, no significant Y-chromosomal sequence diversity has been detected. We used high throughput sequencing technology to identify the first polymorphic Y-chromosomal markers useful for tracing paternal lines. The nucleotide variability of the modern horse Y chromosome is extremely low, resulting in six haplotypes (HT), all clearly distinct from the Przewalski horse (E. przewalskii). The most widespread HT1 is ancestral and the other five haplotypes apparently arose on the background of HT1 by mutation or gene conversion after domestication. Two haplotypes (HT2 and HT3) are widely distributed at high frequencies among modern European horse breeds. Using pedigree information, we trace the distribution of Y-haplotype diversity to particular founders. The mutation leading to HT3 occurred in the germline of the famous English Thoroughbred stallion “Eclipse” or his son or grandson and its prevalence demonstrates the influence of this popular paternal line on modern sport horse breeds. The pervasive introgression of Thoroughbred stallions during the last 200 years to refine autochthonous breeds has strongly affected the distribution of Y-chromosomal variation in modern horse breeds and has led to the replacement of autochthonous Y chromosomes. Only a few northern European breeds bear unique variants at high frequencies or fixed within but not shared among breeds. Our Y-chromosomal data complement the well established mtDNA lineages and document the male side of the genetic history of modern horse breeds and breeding practices.
Zootaxa 3636 (1): 401–420 (5 Apr. 2013)
A new species of Bachia Gray, 1845 (Squamata: Gymnophthalmidae) from the western Brazilian Amazonia
MAURO TEIXEIRA JR, FRANCISCO DAL VECHIO, PEDRO M. SALES NUNES, ANTONIO MOLLO NETO, LUCIANA MOREIRA LOBO, LUIS FERNANDO STORTI, RENATO AUGUSTO JUNQUEIRA GAIGA, PEDRO HENRIQUE FREIRE DIAS, MIGUEL TREFAUT RODRIGUES
A new species of Bachia of the B. dorbignyi group, Bachia scaea sp. nov., is described from the left bank of the upper
Madeira River, at Rondônia state, at the western Brazilian Amazonia. The new species resembles morphologically B. dorbignyi and B. peruana, and seems to be related with the former species based on molecular data (16S and c-mos sequences). Nonetheless the presence of a first temporal separating parietal and supralabial scales and the absence of clawed fingers in the new species, can promptly distinguish it from their close relatives. This description ends with several-decades of stasis in the taxonomy of the Bachia dorbignyi group from Amazonian lowlands, and also presents new evidence that supports the Madeira River as a vicariant barrier.
Zootaxa 3636 (1): 421–438 (5 Apr. 2013)
A new species of porcupine, genus Coendou (Rodentia: Erethizontidae) from the Atlantic forest of northeastern Brazil
ANTONIO ROSSANO MENDES PONTES, JOSÉ RAMON GADELHA, ÉVERTON R. A. MELO, FABRÍCIO BEZERRA DE SÁ, ANA CAROLINA LOSS, VILACIO CALDARA JUNIOR, LEONORA PIRES COSTA & YURI L. R. LEITE
We report the discovery of a new species of Coendou (Rodentia, Erethizontidae), here designated Coendou speratus sp. nov. This small porcupine, locally known as coandu-mirim, is found in the Pernambuco Endemism Centre in the Atlantic coast of northeastern Brazil north of the São Francisco river, one of the most important known biodiversity hotspots. The geographic range of C. speratus overlaps with that of the larger, widespread C. prehensilis, but not with that of C. insidiosus from the southeastern Atlantic forest, nor with that of C. nycthemera, an eastern Amazonian species. Coendou speratus is a small-bodied, long-tailed species that appears to be completely spiny because it lacks long dorsal fur. The dorsal quills have conspicuously brownish red tips that contrast with the blackish dorsal background color. The new species is overall similar to C. nycthemera, but the dorsal body quills are typically tricolored in the former and bicolored in the latter. The new species is externally very distinct from C. insidiosus, especially because the latter has bicolored dorsal quills that are almost completely hidden beneath longer and homogeneous pale or dark hairs.
Zootaxa 3636 (1): 463–475 (5 Apr. 2013)
A new species of Bolitoglossa (Caudata, Plethodontidae) from the continental divide of western Panama
ANDREAS HERTZ, SEBASTIAN LOTZKAT & GUNTHER KÖHLER
We describe the new salamander species Bolitoglossa jugivagans from the Atlantic slopes of the Fortuna depression in western Panama on the basis of morphological and molecular data. Based on mtDNA data, the new species seems to be closely related to B. aureogularis and B. robinsoni, with which it forms a subclade within the subgenus Eladinea.
Rebecca A. Kelley, Frank R. Castelli, Karen E. Mabry, Nancy G. Solomon
Effects of experience and avpr1a microsatellite length on parental care in male prairie voles (Microtus ochrogaster)
Behavioral Ecology and Sociobiology, April 2013
Pair-bonded males often make substantial contributions to the care of their offspring. Male parental behavior may be affected by a range of factors, including previous experience (parental or alloparental), genetic influences, and contributions by the female partner. Previous studies have shown that a microsatellite polymorphism in the regulatory region of the avpr1a gene influences aspects of paternal behavior in male prairie voles (Microtus ochrogaster). Specifically, males with longer avpr1a microsatellites groomed offspring more than did males with shorter avpr1a microsatellites. Previous experience with alloparental care also appears to influence subsequent paternal care in prairie voles. We investigated the influence of avpr1a microsatellite length and previous parental experience on paternal behavior in prairie voles two generations from the field and specially bred to exaggerate differences in avpr1a microsatellite length. We found that avpr1a microsatellite length alone did not affect any of the paternal behaviors that we measured. In contrast, males differed in parental behavior between first and second litters. Regardless of avpr1a microsatellite length, males licked/groomed the second litter less, and retrieved pups more quickly during the second compared to the first litter. Our results show that previous paternal experience may play a more important role than the length of the microsatellite in the regulatory region of the avpr1a gene in influencing paternal care.
Zhishu Xiao, Xu Gao, Zhibin Zhang
The combined effects of seed perishability and seed size on hoarding decisions by Pére David’s rock squirrels
Behavioral Ecology and Sociobiology, April 2013
The food perishability hypothesis reasons that the perishability of nondormant acorns through rapid germination is the primary determinant of hoarding decisions (e.g., embryo removal in nondormant acorns in particular) by scatter-hoarding squirrels. However, we do not know whether seed size and its interactions with seed germination schedule affect squirrel’s hoarding decisions. By presenting pairs of acorns with contrasting germination/dormancy conditions and seed size, we investigated the relative importance of each target trait in determining the hoarding decisions of free-ranging Pére David’s rock squirrel (Sciurotamias davidianus) in Central China. Consistent with the food perishability hypothesis, the squirrels were highly sensitive to subtle differences of acorn germination status either within nondormant acorns or between nondormant and dormant acorns. Though there were no significant differences in seed hoarding and dispersal distance, the embryo-removal probability of nondormant acorns (especially those germinated) was much higher than that of dormant acorns prior to hoarding. Our results also support the seed size hypothesis. Large acorns were often hoarded more and moved farther than small acorns, and large nondormant acorns also had a higher probability of having their embryos removed. Moreover, the interactions between seed size and seed germination schedule had a large effect on whether a given acorn was hoarded or hoarded with its embryo removed. Our study indicates that the combined effects from seed germination schedule and seed size have the potential to determine hoarding decisions of scatter-hoarding squirrels.
R. P. Manassa, M. I. McCormick, D. P. Chivers
Socially acquired predator recognition in complex ecosystems
Behavioral Ecology and Sociobiology, April 2013
Social animals acquire information on predator identities through social learning, where individuals with no prior experience learn from experienced members of the group. However, a large amount of uncertainty is often associated with socially acquired information especially in cases of cross-species learning. Theory predicts that socially acquired information from heterospecifics should take more repetitions to develop in complex ecosystems where the number of participants is greater. Our work focuses on coral reef fish as their social and communal lifestyles, along with their complex life histories, make them an ideal model to test for socially acquired predator recognition. Specifically, we tested if Pomacentrus wardi were capable of transmitting the recognition of an unknown predator, Pseudochromis fuscus, to closely related Pomacentrus moluccensis and phylogenetically distant Apogon trimaculatus. Individuals of both species were able to learn the predator’s identity from experienced P. wardi based on a single conditioning event. It is somewhat surprising how fast social learning occurred particularly for the distantly related cardinalfish. This study demonstrates the widespread nature of social learning as a method of predator recognition in biologically complex ecosystems, and highlights that the benefits of responding to uncertain information may override the costs associated with lost foraging opportunities.
Daniel A. Warner, Clint D. Kelly, Matthew B. Lovern
Experience affects mating behavior, but does not impact parental reproductive allocation in a lizard
Behavioral Ecology and Sociobiology, April 2013
Investment into reproduction is influenced by multiple factors and varies substantially between males and females. Theory predicts that males should adjust their ejaculate size or quality in response to variation in female experience or phenotypic quality. In addition, sperm investment by males may also be influenced by their own status and experience. Although such adjustments of male ejaculate size can impact reproductive success (via fertilization success), fitness returns from male sperm investment may be influenced (either limited or facilitated) by the level of maternal investment. To test this hypothesis, we conducted an experiment that simultaneously evaluated the effect of paternal and maternal experience (which incorporates mating status, age, body size, and other related variables) on paternal sperm investment and maternal reproductive allocation in the lizard Anolis sagrei. During staged mating trials, experienced males were more likely to copulate with females, but these individuals were less likely to transfer sperm during mating than were naïve individuals. Maternal experience had no impact on these mating behaviors. In contrast to expectations, experience and phenotypic quality (of both sexes) had no impact on male ejaculate size or quality (proportion of live sperm) or on maternal reproductive investment (in terms of egg size and yolk steroids). These findings were intriguing given the mating system and past evidence for differential maternal investment in relation to sire quality in A. sagrei. The results found in this study highlight the complexity of reproductive investment patterns, and we urge caution when applying general conclusions across populations or taxa.
Marlies Heesen, Sebastian Rogahn, Julia Ostner, Oliver Schülke
Food abundance affects energy intake and reproduction in frugivorous female Assamese macaques
Behavioral Ecology and Sociobiology, April 2013
In most mammals, female fertility and reproduction are strongly influenced by nutritional status and, therefore, by foraging conditions. Here, we investigate the relationship between food resources, feeding competition, energy intake and reproduction in a group of wild female Assamese macaques (Macaca assamensis) in northeastern Thailand. Over 2,100 h of data on feeding behaviour, energy intake and activity budgets were combined with data on resource characteristics, female reproduction and physical condition. We found that an increase in food availability had a positive effect on female energy intake and conception rates. In addition, it appeared that females incurred energetic costs during lactation and that females with a better physical condition during the mating season were more likely to conceive. The annual birth season occurred a few months before the annual peak in food availability, causing peak lactation to coincide with a period of high food availability. This suggests that females use the increased food abundance to compensate for the energetic costs of lactation. Neither energy intake rates nor activity budgets were influenced by female dominance rank, even during periods when the levels of contest competition were predicted to be high. In line with this, we found no evidence for rank-related differences in reproduction. The apparently limited influence of feeding competition in female Assamese macaques adds to the debate on the extent to which patterns in feeding competition and fitness can reliably be predicted based on ecological conditions. We suggest that this may partially be resolved by including potential competition-reducing mechanisms into the predictive framework.
Arnaud Da Silva, Valentijn van den Brink, Guillaume Emaresi, Ester Luzio, Pierre Bize, Amélie N. Dreiss, Alexandre Roulin
Melanin-based colour polymorphism signals aggressive personality in nest and territory defence in the tawny owl (Strix aluco)
Behavioral Ecology and Sociobiology, April 2013
Nest and territory defence are risky and potentially dangerous behaviours. If the resolution of life history trade-offs differs between individuals, the level of defence may also vary among individuals. Because melanin-based colour traits can be associated with life history strategies, differently coloured individuals may display different nest and territory defence strategies. We investigated this issue in the colour polymorphic tawny owl (Strix aluco) for which plumage varies from dark to light reddish melanic. Accordingly, we found that (1) our presence induced a greater response (flying around) from dark-coloured than light-coloured females and (2) dark reddish males suffered lower nest predation rates than light-coloured males. In experimentally enlarged broods, the probability that females reacted after we played back the hoot calls of a stranger male was higher if these females were lighter reddish; the opposite pattern was found in experimentally reduced broods with dark parents being more reactive than light parents. Finally, darker females alarmed more frequently when paired with a light than with a dark male, suggesting that partners adjust their behaviour to each other. We also tested whether colouration is used as a signal by conspecifics to adjust the level of their defensive behaviour. Accordingly, breeding females responded more vigorously to a dark than a light reddish stuffed tawny owl placed beside their nest. We conclude that melanin-based colouration is a signal of alternative nest and territory defence behaviour that depends on ecological factors.
Trevor A. Branch, Aaron S. Lobo, Steven W. Purcell, Opportunistic exploitation: an overlooked pathway to extinction, Trends in Ecology & Evolution, Available online 5 April 2013, ISSN 0169-5347, 10.1016/j.tree.2013.03.003.
How can species be exploited economically to extinction? Past single-species hypotheses examining the economic plausibility of exploiting rare species have argued that the escalating value of rarity allows extinction to be profitable. We describe an alternative pathway toward extinction in multispecies exploitation systems, termed ‘opportunistic exploitation’. In this mode, highly valued species that are targeted first by fishing, hunting, and logging become rare, but their populations can decline further through opportunistic exploitation while more common but less desirable species are targeted. Effectively, expanding exploitation to more species subsidizes the eventual extinction of valuable species at low densities. Managers need to recognize conditions that permit opportunistic depletion and pass regulations to protect highly desirable species when exploitation can expand to other species.
International Journal of ZoologyVolume 2013 (2013), http://dx.doi.org/10.1155/2013/452329
Claudine Tekounegning Tiogué, Minette Tabi Eyango Tomedi, and Joseph Tchoumboué
Reproductive Strategy of Labeobarbus batesii (Boulenger, 1903) (Teleostei: Cyprinidae) in the Mbô Floodplain Rivers of Cameroon
Aspects of the reproductive strategy of African carp, Labeobarbus batesii, were investigated from May 2008 to October 2009 in the Mbô Floodplain of Cameroon. Samples were collected monthly from artisanal fishermen. The total length and total body mass of each specimen were measured to the nearest mm and 0.01 g, respectively. Sex was determined by macroscopic examination of the gonads after dissection. The sex ratio was female skewed (overall sex ratio: 1 : 1.42). Females reach sexual maturity at a larger size (213 mm) than the males (203 mm). The mean gonadosomatic index ranges from 0 . 3 2 ± 0 . 1 7 % to 1 . 9 1 ± 1 . 1 5 %, whereas the mean K factor ranges from 0 . 9 0 ± 1 . 0 9 to 1 . 1 0 ± 0 . 1 3 . These two parameters are negatively correlated. The reproduction cycle begins in mid-September and ends in July of the next year, and they are reproductively quiescent for the rest of the year. Labeobarbus batesii is a group-synchronous spawner with pulses of synchronised reproduction spread over a long period. The mean absolute, potential, and relative fecundities are 2 8 9 8 ± 2 8 3 7 oocytes, 1 0 1 6 ± 9 6 3 oocytes, and 9 0 7 1 ± 7 1 8 4 oocytes/kg, respectively. The fecundity is higher and positively correlated with the gonad mass than with body size. Its reproductive biology suggests that L. batesii is suitable for pond culture.