Darwin’s
finches and Galápagos
Darwin’s finches of
the Galápagos are classic example of adaptive radiation, having split from a
common ancestor into 14 recognized species in the space of a few million years.
The different species have beak sizes and shapes that are best suited for
feeding on different food types, such as
insects, plants, or different seeds sizes. An example of this diversity can be
seen here.
I have also created a video explaining the radiation:
Our work focuses on
the early stages of adaptive radiation. Specifically, some populations of
finches within a species have bimodal beak size distributions, with one mode
composed of a small-beaked morph (left side of the photo) and the other of a
large-beaked morph (right side of the photo). These two morphs have probably
arisen because two different resources are available: hard seeds, for which
large beaks are most appropriate, and soft seeds, for which small beaks are
most appropriate. These sympatric beak-size morphs within species are thus a
small-scale version of the differences among established species, suggesting
that the morphs can be used to understand the early stages of adaptive
radiation. Part of our work is focused on determining whether large- and
small-beaked morphs do indeed specialize on different foods (i.e., divergent
selection). We are also asking whether this adaptive split has led to
assortative mating, reductions in gene flow, and the onset of speciation.
We have also found
that a formerly bimodal population of finches has lost this property in concert
with an increase in human population size at Academy Bay on Santa Cruz Island (Hendry
et al. 2006; De
León et al. 2011). This suggests that humans alter food resource distributions
in ways that reverse the process of speciation and cause incipient species to
fuse back together. We suggest that this change is the result of the
introduction of plants and the feeding of finches, both of which may reduce
selection against intermediate beak sizes. This improved fitness of
intermediate forms thus breaks one of the barriers keeping different beak sizes
as separate gene pools – in essence halting or reversing speciation. This
research was featured on the CBC radio programs Quirks
and Quarks and, more recently, All-In-A-Weekend.
More
video
·
Journeys
in Search of Darwin’s Finches
Blog
posts:
·
Evolution coming undone in Galapagos
·
The Living Dead: Darwin's finches and Museums
·
Suskewiet! Finchy parallelisms
Photographs
Publications:
1.
Carvajal-Endara,
S., A.P. Hendry, N. Emery, and T.J. Davies. 2017. Habitat filtering not
dispersal limitation shapes oceanic island floras: species assembly of the
Galápagos archipelago. Ecology Letters
20:495-504. PDF
2.
Chaves, J.A.,
E.A. Cooper, A.P. Hendry, J. Podos, L.F. De León,
J.A.M. Raeymaekers, W. O. McMillan, and J. A. C. Uy.
2016. Genomic variation at the tips of the adaptive radiation of Darwin’s
finches. Molecular Ecology
25:5282-5295. PDF
3.
De León, L. F.,
J. Podos, T. Gardezi, A. Herrel, and A.P. Hendry.
2014. Darwin’s finches and their diet niches: the sympatric co-existence of
imperfect generalists. Journal of
Evolutionary Biology 27:1093-1104. PDF
4.
De León, L. F., G. Rolshausen, E. Bermingham, J.
Podos, and A. P. Hendry. 2012. Individual specialization and the seeds of
adaptive radiation in Darwin’s finches. Evolutionary
Ecology Research 14:365-380. PDF
5.
De León, L.F., J.A.M. Raeymaekers, E. Bermingham, J.
Podos, A. Herrel, and A.P. Hendry. 2011.
Exploring possible human influences on the evolution of Darwin’s finches. Evolution 65:2258-2272. PDF
6.
De León, L.F., E. Bermingham, J. Podos, and A.P. Hendry. 2010. Divergence
with gene flow as facilitated by ecological differences: within-island
variation in Darwin’s finches. Philosophical
Transactions of the Royal Society. B. Biological Sciences 365:1041–1052. PDF
7.
Hendry, A.P., S.K. Huber, L. De León, A. Herrel, and J.
Podos. 2009.
Disruptive selection in a bimodal population of Darwin’s finches. Proceedings of the Royal Society B.
Biological Sciences 276:753-759. PDF
8.
Herrel, A., J. Podos, B. Vanhooydonck, and A.P.
Hendry. 2009. Force-velocity trade-off in Darwin’s finch jaw function: a
biomechanical basis for ecological speciation? Functional Ecology 23:119-125. PDF
9.
Foster, D., J. Podos, and A.P. Hendry. 2008. A
geometric morphometric appraisal of beak shape in Darwin’s finches. Journal of Evolutionary Biology
21:263-275. PDF
10.
Huber, S.K., L.F. De Leon, A.P. Hendry, E. Bermingham,
and J. Podos. 2007. Reproductive isolation of sympatric morphs in a population
of Darwin’s finches. Proceedings of the
Royal Society B. Biological Sciences 274:1709-1714. PDF
11.
Hendry, A.P., P.R. Grant, B.R. Grant, H.A. Ford, M.J.
Brewer, and J. Podos. 2006. Possible human impacts on adaptive radiation: beak
size bimodality in Darwin’s finches. Proceedings
of the Royal Society B. Biological Sciences. 273:1887-1894. PDF.
12.
Herrell, J. Podos, S.K. Huber, and A.P. Hendry. 2005.
Evolution of bite force in Darwin’s finches: a key role for head width. Journal of Evolutionary Biology
18:669-675. PDF
13.
Herrel, A., J. Podos, S.K. Huber, and A.P. Hendry.
2005. Bite performance and morphology in a population of Darwin’s finches:
implications for the evolution of beak shape. Functional Ecology. 19:43-48. PDF
“Darwin’s
finches are dull to look at, not only in their orderly ranks in museum trays,
but also when they hop about the ground or perch in the trees of the Galapagos,
making dull unmusical noises.” (Lack 1947)
Back to Hendry lab page.