The Difficulty of Predicting Evolutionary Change in Response to Novel Ecological Interactions: A Field Experiment with Lizards.

AbstractDetermining whether and how evolution is predictable is an important goal, particularly as anthropogenic disturbances lead to novel species interactions that could modify selective pressures. Here, we use a multigeneration field experiment with brown anole lizards () to test hypotheses about the predictability of evolution. We manipulated the presence/absence of predators and competitors of across 16 islands in the Bahamas that had preexisting brown anole populations.

Predator-induced collapse of niche structure and species coexistence.

Biological invasions are both a pressing environmental challenge and an opportunity to investigate fundamental ecological processes, such as the role of top predators in regulating biodiversity and food-web structure. In whole-ecosystem manipulations of small Caribbean islands on which brown anole lizards (Anolis sagrei) were the native top predator, we experimentally staged invasions by competitors (green anoles, Anolis smaragdinus) and/or new top predators (curly-tailed lizards, Leiocephalus carinatus). We show that curly-tailed lizards destabilized the coexistence of competing prey species, contrary to the classic idea of keystone predation.

Hybridization and rapid differentiation after secondary contact between the native green anole () and the introduced green anole ().

In allopatric species, reproductive isolation evolves through the accumulation of genetic incompatibilities. The degree of divergence required for complete reproductive isolation is highly variable across taxa, which makes the outcome of secondary contact between allopatric species unpredictable. Since before the Pliocene, two species of lizards, and , have been allopatric, yet this period of independent evolution has not led to substantial species-specific morphological differentiation, and therefore, they might not be reproductively isolated.

Untangling intra- and interspecific effects on body size clines reveals divergent processes structuring convergent patterns in Anolis lizards.

Bergmann's rule-the tendency for body size to increase in colder environments-remains controversial today, despite 150 years of research. Considerable debate has revolved around whether the rule applies within or among species. However, this debate has generally not considered that clade-level relationships are caused by both intra- and interspecific effects.