Developmental environment contributes to rapid trait shifts among newly colonized subterranean habitats

Recent colonization of extreme environments provides unique opportunities to study the early steps of adaptation and the potential for rapid convergent evolution.However,phenotypic shifts during recent colonization may also be due to plasticity in response to changes in the rearing environment.Here,we analyzed a suite of morphological and behavioral traits in paired surface,subterranean,and facultatively subterranean Mexican tetras(Astyanax mexicanus)from recent introductions in two separate watersheds outside of their native range.We found a variety of phenotypic and behavioral shifts between subterranean and surface populations that are similar to those observed in relatively ancient populations in Mexico.Despite this rapid morphological divergence,we found that most of these trait differences were due to plasticity in response to rearing environments.While most trait assays in common-garden,lab-raised fish indicated that phenotypic shifts in wild fish were the result of plasticity,we also found evidence of genetic control in several traits present in subterranean populations.Interestingly,wall-following behavior,an important subterranean foraging behavior,was greater in lab-born subterranean fish than in lab-born surface fish,suggesting rapid divergence of this trait between subterranean and surface populations.Thus,this study sheds light on the early steps of subterranean evolution,identifies potential rapid behavioral evolution,and suggests that plasticity in traits involving exploratory behavior may facilitate subterranean colonization.

Mitogenomes of historical type specimens unravel the taxonomy of sportive lemurs(Lepilemur spp.)in Northwest Madagascar

Accurate information on name-bearing types,including corresponding type localities,is essential for proper taxonomy.However,such geographic information is often missing or unreliable.The localities of type specimens collected 100–200 years ago can be difficult to trace due to changes in local names or simple inaccuracies.Such a case can be found for the gray-backed sportive lemur(Lepilemur dorsalis),with its type locality imprecisely fixed as Northwest Madagascar.In recent years,eight species have been newly described for the Inter-River-Systems(IRSs)of this region,however the designation of L.dorsalis remains controversial due to a lack of a precise type locality.Here,we sequenced the complete mitochondrial genomes(mitogenomes)of type specimens of L.dorsalis and L.grandidieri,which is currently recognized as a synonym of L.dorsalis and compared their sequences with those of samples of known provenance from different IRSs.Results showed that the two type specimens of L.dorsalis and L.grandidieri had identical mitogenome sequences and clustered closely with samples collected in IRS V,indicating that the type locality could be fixed to IRS V.Consequently,L.dorsalis occurs in IRS V,and L.grandidieri and L.mittermeieri are junior synonyms of L.dorsalis.This finding demonstrates the value of type specimens for clarifying phylogeographic and taxonomic questions and clarifies the taxonomy of sportive lemurs in Northwest Madagascar.