Evolution of Character Displacement in Darwin's Finches

  title={Evolution of Character Displacement in Darwin's Finches},
  author={Peter R. Grant and Barbara Rosemary Grant},
  pages={224 - 226}
Competitor species can have evolutionary effects on each other that result in ecological character displacement; that is, divergence in resource-exploiting traits such as jaws and beaks. [] Key Result The observed evolutionary response to natural selection was the strongest recorded in 33 years of study, and close to the value predicted from the high heritability of beak size. These findings support the role of competition in models of community assembly, speciation, and adaptive radiations.

Reproductive isolation of sympatric morphs in a population of Darwin's finches

It is demonstrated that the two morphs show strong positive assortative pairing, a pattern that holds over three breeding seasons and during both dry and wet conditions, and provides strong support for the central role of ecology during the early stages of adaptive radiation.

Fission and fusion of Darwin's finches populations

  • B. GrantP. Grant
  • Biology
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2008
It is proposed that introgression has the largest effect on the evolution of interbreeding species after they have diverged in morphology, but before the point is reached when genetic incompatibilities incur a severe fitness cost.

Experimental demonstration of ecological character displacement

This accordion-like dynamic provides direct experimental evidence that competition for resources can cause evolutionary shifts in resource-related characters.

Disruptive selection in a bimodal population of Darwin's finches

Analysis of patterns of selection in the medium ground finch of El Garrapatero, Santa Cruz Island, Galápagos suggests a dynamic tug of war among factors such as selection and assortative mating, which may alternatively promote or constrain divergence during adaptive radiation.

Character Displacement and the Origins of Diversity

The empirical support for Darwin’s principle of divergence of character is examined, specifically that (1) competition promotes divergent trait evolution, (2) the strength of competitively mediated divergent selection increases with increasing phenotypic similarity between competitors, (3) divergence can occur within species, and (4)competitively mediated divergence can trigger speciation.

Evolutionary Dead End in the Galápagos: Divergence of Sexual Signals in the Rarest of Darwin's Finches

Striking differences in mating signals, morphology and genetics between the two remnant populations of Darwin's mangrove finch Camarhynchus heliobates are reported, and it is shown that territorial males exhibited strong discrimination of sexual signals by locality.

Rapid evolution of a native species following invasion by a congener

On small islands in Florida, it is found that the lizard Anolis carolinensis moved to higher perches following invasion by Anolis sagrei and, in response, adaptively evolved larger toepads after only 20 generations, illustrating that interspecific interactions between closely related species can drive evolutionary change on observable time scales.

Ecological and morphological determinants of evolutionary diversification in Darwin's finches and their relatives

Analysis of the evolutionary dynamics of speciation and trait diversification in Thraupidae illustrates how the exploitation of ecological opportunity by contrasting means can produce clades with similarly high diversification rate yet strikingly different degrees of ecological and morphological differentiation.

Darwin's finches and their diet niches: the sympatric coexistence of imperfect generalists

The results together suggest that the ground finches are ‘imperfect generalists’ that use overlapping resources under benign conditions, but then retreat to resources for which they are best adapted during periods of food limitation, which likely promote local and regional coexistence.

Sisyphean evolution in Darwin's finches

It is argued that the six putative ground finch species of the Galápagos Islands represent a dramatic example of Sisyphean evolution that has been confused with the standard model of speciation, and the pattern of morphological, behavioural and genetic variation supports recognition of a single species of Geospiza, which is suggested should be recognized as Darwin's groundfinch.



Ecological Character Displacement in Darwin's Finches

Character displacement resulting from interspecific competition has been extremely difficult to demonstrate, but a study of Darwin's ground finches provides strong evidence for character displacement.

Recurrent patterns of natural selection in a population of Darwin's finches

It is shown that in two subsequent periods of moderate to high adult mortality (1980 and 1982), the population was subject to the same selection as before, and beak depth and body weight were commonly under direct selection to increase but, surprisingly, beak width was directly selected to decrease.

Oscillating selection on Darwin's finches

A reversal in the direction of selection following the opposite climatic extreme is documented, and the connection between oscillating selection and fluctuations in food supply is demonstrated.

Unpredictable Evolution in a 30-Year Study of Darwin's Finches

Continuous, long-term studies are needed to detect and interpret rare but important events and nonuniform evolutionary change in Darwin's finches on the Galápagos island of Daphne Major.

Character Release and Displacement in Fishes: A Neglected Literature

It is shown that competition is frequently a diversifying force that creates differences between species and differences within species when other closely related species are absent, and the lake environment can be viewed as a set of non-Hutchinsonian or "environmental" niches that exist apart from the species that occupy them.


Evaluating two causes of character divergence in feeding morphology between tadpoles of two species of spadefoot toads found that, in natural ponds containing both species, S. multiplicata almost always developed into a smaller, round-bodied tadpole with normal sized jaw muscles used for feeding on detritus at the pond bottom (the “omnivore” morph), whereas S. bombifrons almost always developing into a larger tadpole.

Ecological Character Displacement in Adaptive Radiation

The evidence suggests that character displacement occurs frequently in nature, and it probably plays an important role in the evolution of diversity in many adaptive radiations.

Experimental Evidence That Competition Promotes Divergence in Adaptive Radiation

Disproportionately severe competition between similar phenotypes indicates frequency-dependent selection, verifying a crucial element of theory of competition and character divergence and resolving outstanding debates on the ecological causes of diversification and the evolutionary consequences of competitive interactions.

Convergent and divergent character displacement

It is concluded that the evidence for the ecological aspect of character displacement is weak and the principal ideas in the original definition given by Brown & Wilson (1956) are retained.

The classical case of character release: Darwin's finches (Geospiza) on Isla Daphne Major, Galápagos

The Daphne fortis phenotype probably represents a balance between introgression with fuliginosa, selection for larger body size in dry years and selection for smaller body sizeIn wet years, and should be qualified to reflect the ecological complexity of the situation.