Adaptive evolution of the lower jaw dentition in Mexican tetra (Astyanax mexicanus)
Atukorala AD, Hammer C, Dufton M, Franz-Odendaal TA
EvoDevo 2013, 4 :28 (7 October 2013)
The Mexican tetra (Astyanax mexicanus) has emerged as a good animal model to study the constructive and regressive changes associated with living in cave environments, as both the ancestral sighted morph and the cave dwelling morph are extant. The cave dwelling morphs lack eyes and body pigmentation, but have well developed oral and sensory systems that are essential for survival in dark environments. The cave forms and surface forms are interfertile and give rise to F1 hybrids progeny known as intermediates. In cavefish, degeneration of the lens is one of the key events leading to eye regression. We have previously shown that surgical lens removal in surface fish embryos has an effect on the craniofacial skeleton. Surprisingly, lens removal was also found to have an effect on the caudal teeth in the lower jaw. In order to understand this result, we analyzed the lower jaw and upper jaw dentitions of surface, cavefish and F1 hybrids of surface and cavefish and compared our findings with surface fish that underwent lens removal. We also investigated the upper jaw (premaxillae and maxillae) dentition in these fish.
Our tooth analyses shows that cavefish have the highest numbers of teeth in the mandible and maxillae, surface forms have the lowest numbers and F1 hybrids are between these groups. These differences are not observed in the premaxillae. A wide diversity of cuspal morphology can also be found in these fish. Jaw size also differs amongst the groups, with the mandible exhibiting the greatest differences. Interestingly, tooth number in surgery fish is different only in the caudal region of the mandible; this is the region that is constrained in size in all morphs.
Our data provides the first detailed description of the jaw dentitions of two morphs of Astyanax mexicanus, as well as in F1 hybrids. Tooth number, patterning and cuspal morphology are enhanced in cavefish in all jaws. This is in contrast to the increase in tooth number previously observed on the lens ablated side of the surgery fish. These findings indicate that the mechanisms which govern the constructive traits in cavefish are different to the mechanisms causing an increase tooth number in surgery fish.
Diversity and distribution of reptiles in Romania
Dan Cogălniceanu, Laurentiu Rozylowicz, Paul Székely, Ciprian Samoilă, Florina Stănescu, Marian Tudor, Diana Székely, Ruben Iosif
ZooKeys 341 (2013): 49-76, doi: 10.3897/zookeys.341.5502
The reptile fauna of Romania comprises 23 species, out of which 12 species reach here the limit of their geographic range. We compiled and updated a national database of the reptile species occurrences from a variety of sources including our own field surveys, personal communication from specialists, museum collections and the scientific literature. The occurrence records were georeferenced and stored in a geodatabase for additional analysis of their spatial patterns. The spatial analysis revealed a biased sampling effort concentrated in various protected areas, and deficient in the vast agricultural areas of the southern part of Romania. The patterns of species richness showed a higher number of species in the warmer and drier regions, and a relatively low number of species in the rest of the country. Our database provides a starting point for further analyses, and represents a reliable tool for drafting conservation plans.
Zootaxa 3718 (6): 561–574 (9 Oct. 2013)
A molecular and morphological characterization of Oliver’s parrot snake, Leptophis coeruleodorsus (Squamata: Serpentes: Colubridae) with the description of a new species from Tobago
JOHN C. MURPHY, STEVLAND P. CHARLES, RICHARD M. LEHTINEN & KRISTA L. KOELLER
Currently, two snake species of the genus Leptophis occur in Trinidad and Tobago. One, L. stimsoni, is endemic to Trini- dad’s Northern Range and known from relatively few specimens. The second is the diurnal, arboreal, brightly colored par- rot snake Leptophis coeruleodorsus Oliver. It was originally described based on 23 specimens from Trinidad, Tobago, and four locations in northern Venezuela but remains poorly known. It was later assigned as a subspecies of Leptophis ahaet- ulla; a widespread, polytypic species. Here we compare 11 specimens of the L. ahaetulla Group using DNA sequences from two mitochondrial genes (cytochrome b and 16S, 1,383 bp total) from island and mainland populations, report on the variation in the morphology of 54 museum specimens of Leptophis a. coeruleodorsus; describe the previously unde- scribed holotype of L. coeruleodorsus Oliver, and restrict its type locality. Additionally, we describe a new species of Leptophis from the island of Tobago that can be distinguished from L. coeruleodorsus on the basis of snout shape, upper labial architecture, elongated prefrontal scales, and ventral scale counts. The new Leptophis raises the number of endemic Tobago amphibians and reptiles to 11 taxa.
Zootaxa 3718 (6): 583–590 (9 Oct. 2013)
Schistura maculosa, a new species of loach (Teleostei: Nemacheilidae) from Mizoram, northeastern India
SAMUEL LALRONUNGA, LALNUNTLUANGA & LALRAMLIANA
Schistura maculosa, a new species of loach, is described from Tuingo and Pharsih Rivers, tributaries of Tuivai River (Ba- rak drainage) in Mizoram, northeastern India. It is distinguished from other closely related Schistura species in having an axillary pelvic lobe; an incomplete lateral line; 20–30 narrow black bars on the body; 3–4 rows of black spots horizontally across the dorsal-fin; a slightly emarginate caudal-fin, with 5–7 rows of black spots more or less regularly arranged ver- tically on rays across the fin, and 8+8 branched caudal-fin rays.
E. Fabbri, R. Caniglia, J. Kusak, A. Galov, T. Gomerčić, H. Arbanasić, D. Huber, E. Randi, Genetic structure of expanding wolf (Canis lupus) populations in Italy and Croatia, and the early steps of the recolonization of the Eastern Alps, Mammalian Biology – Zeitschrift für Säugetierkunde, Available online 12 October 2013, ISSN 1616-5047, http://dx.doi.org/10.1016/j.mambio.2013.10.002.
After centuries of range contraction and demographic declines wolves are now expanding in Europe, colonizing regions from where they have been absent for centuries. Wolf colonizing the western Alps originate by the expansion of the Italian population. Vagrant wolves of Italian and Dinaric-Balkan origins have been recently observed in the Eastern Alps. In this study we compared the genetic structure of wolf populations in Italy and Croatia, aiming to identify the sources of the ongoing recolonization of the Eastern Alps. DNA samples, extracted from 282 Italian and 152 Croatian wolves, were genotyped at 12 autosomal microsatellites (STR), four Y-linked STR and at the hypervariable part of the mitochondrial DNA control-region (mtDNA CR1). Wolves in Croatia and Italy underwent recent demographic bottlenecks, but they differ in genetic diversity and population structure. Wolves in Croatia were more variable at STR loci (NA =7.4, HO =0.66, HE =0.72; n =152) than wolves in Italy (NA =5.3, HO =0.57, HE =0.58; n =282). We found four mitochondrial DNA (mtDNA CR1) and 11 Y-STR haplotypes in Croatian wolves, but only one mtDNA CR1 and three Y-STR haplotypes in Italy. Wolves in Croatia were subdivided into three genetically distinct subpopulations (in Dalmatia, Gorski kotar and Lika regions), while Italian wolves were not sub-structured. Assignment testing shows that the eastern and central Alps are recolonized by wolves dispersing from both the Italian and Dinaric populations. The recolonization of the Alps will predictably continue in the future and the new population will be genetically admixed and very variable with greater opportunities for local adaptations and survival.
Melissa Burns-Cusato, Brian Cusato, Amanda C. Glueck, Barbados green monkeys (Chlorocebus sabaeus) recognize ancestral alarm calls after 350 years of isolation, Behavioural Processes, Available online 12 October 2013, ISSN 0376-6357, http://dx.doi.org/10.1016/j.beproc.2013.09.012.
Vervet monkeys (Chlorocebus pygerythrus) produce alarm calls and anti-predator behaviors that are specific to a threatening predator’s mode of attack. Upon hearing a leopard alarm, the monkeys will run up trees where they are relatively safe. In contrast, eagle alarms prompt the monkeys to run under bushes and snake alarms stimulate bipedal standing. Early researchers proposed that the meaning of each alarm call is conveyed by observational learning. If this true then absence of the predator that elicits the alarm call may lead to alteration or decay of the alarm’s meaning since there is no longer opportunity for observational learning to occur. The present study tested this hypothesis by presenting alarm calls to a closely related species of monkeys (Chlorocebus sabaeus) that have been isolated from their ancestral predators for more than 350 years. The monkeys ran up trees in response to a leopard alarm, but not when the same alarm was played backwards and not in response to a snake alarm. Snake alarms failed to reliably elicit bipedal standing. These results suggest that the leopard alarm call conveys the same information to Barbados green monkeys as West African green monkeys despite generations of isolation from leopards.
Nárgila G. Moura, Alexander C. Lees, Christian B. Andretti, Bradley J.W. Davis, Ricardo R.C. Solar, Alexandre Aleixo, Jos Barlow, Joice Ferreira, Toby A. Gardner, Avian biodiversity in multiple-use landscapes of the Brazilian Amazon, Biological Conservation, Volume 167, November 2013, Pages 339-348, ISSN 0006-3207, http://dx.doi.org/10.1016/j.biocon.2013.08.023.
Habitat loss and degradation is the most pervasive threat to tropical biodiversity worldwide. Amazonia sits at the frontline of efforts to both improve the productivity of tropical agriculture and prevent the loss of biodiversity. To date our understanding of the biodiversity impacts of agricultural expansion in Amazonia is restricted to findings from small scale studies that typically assess the importance of a limited number of land-use types. Here we investigate local and landscape-scale responses of Amazonian avian assemblages to land-cover changes across a gradient of land-use intensity ranging from undisturbed primary forest to mechanised agriculture in 36 drainage catchments distributed across two large regions of the eastern Brazilian Amazon. We found that species richness of forest-associated birds declined progressively along this gradient, accompanied by marked shifts in assemblage composition. We found significant changes in species composition, but not richness, between primary forests that had been subject to different levels of disturbance from logging and fire. Secondary forests retained levels of species richness intermediate between primary forests and production areas, but lacked many forest-dependent species. Production areas (arable crops, cattle pastures and plantation forests) all retained far fewer species than any forest habitat, and were largely dominated by taxa commonly associated with open areas. Diversity partitioning revealed that species composition varied the most among undisturbed forest transects, and steadily decreased with increasing forest degradation and land-use intensity. Our results emphasise the importance of protecting both remaining areas of primary forest in private lands, as well as protecting the same forests from further disturbance events.
Removal of livestock alters native plant and invasive mammal communities in a dry grassland–shrubland ecosystem
Amy L. Whitehead, Andrea E. Byrom, Richard I. Clayton, Roger P. Pech
Biological Invasions October 2013
The impacts of domesticated herbivores on ecosystems that did not evolve with mammalian grazing can profoundly influence community composition and trophic interactions. Also, such impacts can occur over long time frames by altering successional vegetation trajectories. Removal of domesticated herbivores to protect native biota can therefore lead to unexpected consequences at multiple trophic levels for native and non-native species. In the eastern South Island of New Zealand large areas of seral grassland–shrubland have had livestock (sheep and cattle) removed following changes in land tenure. The long-term (>10 years) outcomes for these communities are complex and difficult to predict: land may return to a native-dominated woody plant community or be invaded by exotic plants and mammals. We quantified direct and indirect effects of livestock removal on this ecosystem by comparing plant and invasive mammal communities at sites where grazing by livestock ceased c.10–35 years ago (conservation sites) with paired sites where pastoralism has continued to the present (pastoral sites). There was higher total native plant richness and reduced richness of exotic plants on conservation sites compared with pastoral sites. Further, there were differences in the use of conservation and pastoral sites by invasive mammals: rabbits and hedgehogs favoured sites grazed by livestock whereas house mice, brushtail possums and hares favoured conservation sites. Changes in the relative abundance of invasive mammal species after removal of domesticated livestock may compromise positive outcomes for conservation in successional plant communities with no evolutionary history of mammalian grazing.