Subterranean Waters of Yucatán Peninsula, Mexico Reveal Epigean Species Dominance and Intraspecific Variability in Freshwater Ostracodes (Crustacea: Ostracoda)

Laura Macario-González,Dorottya Angyal,Sergio Cohuo,Liseth Pérez,Maite Mascaró

doi:10.3390/d13020044

Abstract

The Yucatán Peninsula is a karstic region, rich in subterranean environments with a diverse crustacean stygobiont fauna. In order to gain insights into the biological evolution of the subterranean environments of this region, we evaluated the ostracode species composition of caves and cenotes in five independent sampling campaigns (2008, 2013, 2017–2019). Using morphometric analyses, we evaluated inter-population morphological variability; using molecular analysis based on mitochondrial COI and nuclear 18S rDNA, we evaluated genetic differentiation in selected species. The observed fauna is composed of 20 (epigean) species, presenting a lack of strict stygobionts. Morphometric analyses discriminated up to three morphotypes in each of the three most abundant species: Cytheridella ilosvayi, Alicenula sp. and Cypridopsis vidua. High intraspecific morphological variability was found either in shape or size. Phylogenetic analysis based on COI demonstrated the existence of three lineages on C. ilosvayi, with high support (>0.9). The 18S rDNA sequences were identical among individuals of different populations. A lack of congruence between the genetic markers precluded us from postulating speciation in subterranean environments. It is likely that Late Pleistocene—Early Holocene climate variation related to sea level and precipitation was forcing agent for epigean ostracode dominance in subterranean environments of the Peninsula.

Highlights

Introduction iationsSubterranean waters are critical environments for biodiversity
Peninsula; (ii) we evaluate morphological variability in valves and using molecular analyses, we assess the genetic differentiation occurring among subterranean ostracodes, and Diversity 2021, 13, 44 composition from subterranean habitats of the Yucatán Peninsula; (ii) we evaluate morphological variability in valves and using molecular analyses, we assess the genetic differentiation occurring among subterranean ostracodes, and (iii) we discuss role of past (since the(since in structuring the (iii) wethe discuss the roleclimate of pastvariations climate variations the Late Pleistocene) in structuring composition of subterranean ostracode fauna of fauna the Peninsula
For C. ilosvayi, we evaluated a total of 13 individuals from seven populations

Summary

Introduction

Subterranean waters are critical environments for biodiversity. Aquatic species have been able to colonize subterranean environments through morphological, behavioral and physiological adaptations [4,5,6], but given the highly selective environment, the number of species per site (i.e. α diversity) and their ecological interactions are usually limited [1,7,8,9]. Species inhabiting subterranean waters are usually isolated, with a limited capacity of dispersal. These conditions may drive large differences in species composition between regional sites (high β diversity) [10,11]. Speciation and endemicity are common in these environments and are promoted by events such as vicariance and spatial ecological partition of the environment [11,12,13]

Results

Discussion

Conclusion