Evolutionary patterns and processes in the radiation of phyllostomid bats

Area of Science:

• Evolutionary biology
• Mammalogy
• Ecomorphology

Background:

• Phyllostomid bats exhibit extensive ecological and phenotypic radiation, making them a key model for studying cranial ecomorphology.
• Previous studies focused on qualitative descriptions or correlations, lacking explicit tests of evolutionary mechanisms for phenotypic diversification.

Purpose of the Study:

• To test hypotheses regarding the evolutionary processes driving the diversification of mandible shape, size, and diet in phyllostomid bats.
• To investigate the interplay of adaptive and non-adaptive factors in shaping bat phenotypes.

Main Methods:

• Utilized a combination of morphometric and comparative methods.
• Analyzed mandible shape and size variation in relation to diet specializations.

Main Results:

• Phyllostomid lineages radiated into distinct mandible shape spaces, with feeding specializations aligning with different evolutionary axes.
• Mandible size and shape evolved largely independently; shape variation linked to elongation or tooth/process size, not overall size.
• Early diversification (before 20 Mya) showed a burst of shape, size, and diet disparity, followed by relative phenotypic and ecological stasis.
• An Ornstein-Uhlenbeck model with five adaptive peaks (insectivory, carnivory, sanguivory, nectarivory, frugivory) best explained mandible divergence.

Conclusions:

• Phyllostomid bat radiation involved both adaptive and non-adaptive evolutionary components.
• The initial 10 million years saw significant phenotypic and ecological divergence, followed by 20 million years of stasis around adaptive feeding peaks.
• Subsequent speciation likely resulted from non-adaptive allopatric divergence or adaptation to existing dietary niches.