The evolution of body size, both within and between species, has been
long predicted to be influenced by multifarious environmental factors.
However, the specific drivers of body size variation have remained
difficult to understand because of the wide range of proximate factors
that consistently covary with ectotherm body sizes across populations
with varying local environmental conditions. Here, we used a widely
distributed lizard (Eremias argus) collected from different populations
situated across China to assess how climatic conditions and/or available
resources at different altitudes shape the geographical patterns of
lizard body size across populations. We used body size data from
locations differing in altitudes across China to construct linear mixed
models to test the relationship between lizard body size and ecological
and climate conditions across altitudes. Lizard populations showed
significant differences in body size across altitudes. Furthermore, we
found that variation in body size among populations was also explained
by climatic and seasonal changes along the altitudinal gradient.
Specifically, body size decreased with colder and drier environmental
conditions at high altitudes, resulting in a reversal of Bergmann’s
rule. Limited resources at high altitudes, as measured by net primary
productivity, may also constrain body size. Therefore, our study
demonstrates that the intraspecific variation in female lizards’ body
size may be strongly influenced by multifarious local environments as
adaptive plasticity for female organisms to possibly maximise
reproductive ecology along geographic clines.
Background: Copepods are key components of aquatic ecosystems and can help regulate the global carbon cycle. Much attention has been paid to the species diversity of copepods worldwide, but the phylogeography and genetic diversity of copepods in Nigeria is unexplored. Results: Using a mitochondrial cytochrome c oxidase subunit I marker, we preformed phylogenetic and phylogeographic analyses for Cyclopidae copepods in Southeast Nigeria. A high species diversity of Cyclopidae in Nigeria: 5 species of Tropocyclops, 5 species of Mesocyclops and 2 species of Thermocyclops from Cyclopidae were identified in 15 populations. Moreover, we detected 18 unique haplotypes, which fell into two distinct clades. Pairwise genetic distances (uncorrected p-distances) among the species of Cyclopidae ranged from 0.05 to 0.257. Several species co-existed in the same lake, and some haplotypes were shared among different geographic populations, suggesting a dispersal of Cyclopidae in our sampling region. Finally, we found that the population genetic diversity for each species of Cyclopidae was low in Nigeria. Conclusions: Our findings explored the species diversity and distribution of copepods within the family Cyclopidae for 15 Nigerian freshwater ecosystems: a high species diversity of Cyclopidae copepods was detected over a small geographic sampling range. Results from this study contribute to a better understanding of copepod diversity of Nigerian freshwater ecosystems.
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