Diversity-dependent speciation and extinction in hominins.

Area of Science:

• Paleoanthropology
• Evolutionary Biology
• Macroevolutionary Studies

Background:

• Hominin speciation and extinction research often overlooks interspecific competition, focusing instead on climate change.
• Broader vertebrate research indicates a correlation between species diversity and both speciation and extinction rates, highlighting the potential role of competition.

Purpose of the Study:

• To investigate whether hominin speciation and extinction rates exhibit diversity dependence, mirroring patterns observed in other vertebrates.
• To differentiate the roles of interspecific competition and climate change in hominin macroevolution.

Main Methods:

• Estimation of hominin speciation and extinction rates using fossil occurrence data and Bayesian analysis with preservation variability priors.
• Analysis of speciation rates across hominin phylogeny to assess diversity dependence.
• Comparison of diversity-dependence patterns in hominins with broader vertebrate macroevolutionary trends.

Main Results:

• Hominin speciation was generally limited by clade-wide diversity, though the Australopithecus and Paranthropus subclade did not reach these limits before extinction.
• Extinction rates in hominins were not correlated with species diversity, suggesting a stronger influence of climate.
• The genus Homo displayed unusual patterns: positively diversity-dependent speciation and negatively diversity-dependent extinction, rare in the broader tree of life.

Conclusions:

• Biotic interactions, particularly interspecific competition, played a significant and previously underappreciated role in Homo macroevolution, especially in speciation.
• The unique macroevolutionary patterns in Homo may stem from range expansions driven by competition and facilitated by ecological innovations.
• Understanding hominin evolution within the broader vertebrate context offers new insights into evolutionary processes in our own lineage and beyond.