The effects of cryptic diversity on diversification dynamics analyses in Crocodylia

Area of Science:

• Evolutionary Biology
• Ecology
• Genetics

Background:

• Diversification analyses are often biased by incomplete taxon sampling, leading to inaccurate conclusions about speciation rates.
• Previous studies on Crocodylia suggested long-term low diversification rates and recent slowdowns in speciation.
• The impact of cryptic diversity on crocodylian evolution has not been previously investigated.

Purpose of the Study:

• To investigate the effects of incorporating cryptic diversity into diversification dynamics analyses of extant crocodylians.
• To re-evaluate crocodylian evolutionary history by considering hidden species.
• To assess the necessity of cryptic species and taxonomic accuracy in macroevolutionary studies.

Main Methods:

• Inferred a time-calibrated, cryptic-species-level phylogeny for extant crocodylians using cytochrome b gene sequences.
• Compared genetic data from 45 lineages against the 26 formally recognized crocodylian species.
• Applied diversification dynamics analyses to the new phylogeny.

Main Results:

• Diversification rate estimates using the cryptic-species phylogeny indicated increasing speciation and net-diversification rates towards the present.
• This finding contrasts sharply with previous studies suggesting a slowdown in crocodylian speciation.
• The study underscores the significant impact of cryptic diversity on evolutionary rate estimations.

Conclusions:

• Cryptic diversity is crucial for accurate macroevolutionary analyses and understanding biodiversity dynamics.
• Future studies should incorporate cryptic species, though representing extinct cryptic taxa remains a challenge.
• Further research into crocodylian diversification using diverse genomic data is recommended.