The establishment of sedentary populations has several consequences for genetics, morphology and behavior.
Numerous bird species migrate. Occasionally, a migrating population “decides” to stop their annual trips and become sedentary. These migratory drop-offs have been documented in several taxa and often result in morphological and physiological changes. But can they also drive speciation? Theoretically, it is certainly possible that differences in morphology and genetics start to accumulate between migratory and sedentary populations, ultimately resulting reproductive isolation and the origin of new species. A recent study in the journal Current Biology tested this idea in the Fork-Tailed Flycatcher (Tyrannus savana).
Four…
Newly discovered site in the Bahamas houses a hybrid between two groups of mangrove rivulus fish.
Self-fertilization is extremely rare in vertebrates. The mangrove rivulus is the only known vertebrate that routinely reproduces by selfing (teenagers taking selfies do not count). Given this peculiar mode of reproduction, hybridization should be rare. Or so you would think…
Three Groups
The mangrove rivulus currently comprises two species (Kryptolebias marmoratus and K. hermaphroditus), but can be divided into three main groups:
- Northern group in Florida and the Caribbean that corresponds to K. marmoratus
- Southern group in Brazil that corresponds to K. hermaphroditus
- Central group in the Caribbean that probably corresponds to a third…
New study finds exchange of crucial genes between several cow species.
Humans are good at two things: telling stories and domesticating animals. A recent paper in Nature Ecology & Evolution explores both talents by studying the domestication of cows. Dong-Dong Wu and colleagues sequenced the genomes of several cow species (genus Bos) and uncovered a history heavily influenced by hybridization. The interbreeding of several cow species led to the exchange of particular genes, each with its own story to tell.
A quick word of caution. Genome-wide analyses often uncover interesting genes and it is very tempting to tell a story about these genes. We should be careful not to make up just-so-stories, no matter how plausible they might sound. Every gene story should be the starting point for further analyses. …
Coloring outside species boundaries: A ‘super’-cool example of adaptive introgression in butterflies
Although the main topic on this blog is avian hybridization, I occasionally venture into the world of other creatures (see for example here and here). Surprisingly, I have not covered hybridization in butterflies yet. But a recent paper in Current Biology is just too “super” to ignore.
Wondrous Wing-patterns
The butterfly Heliconius numata flutters around Amazonian forests in a variety of color morphs. Each wing-pattern closely matches the colors and shapes of other toxic butterflies. A textbook example of Batesian mimicry. But what is the genetic basis of this color palette? Previous work showed that the wing-pattern morphs are associated with large chromosomal rearrangements. …
A recent paper in Current Opinion in Genetics and Development gives a concise overview of hybridization in primates, including humans.
Let’s start with some numbers. The genetic contribution of one primate species to the genome of another by means of ancient gene flow:
- Tibetan Macaque genomes contain 1–8% DNA from Rhesus Macaques
- Chimpanzee genomes harbor about 1% Bonobo DNA
- Non-African humans have 1 to 5% of Neanderthal DNA (Africans never came into contact with Neanderthals and hence to not have their DNA)
- Modern-day people from Oceania have 4–6% Denisovian (an extinct group of archaic humans) ancestry in their genomes
These figures clearly indicate that gene flow has occurred during primate evolution. The obvious question is: did it matter? Did ancient hybridization influence the evolutionary history of primates? For Neanderthal genes it has been shown that they contribute to depression and the immune system. For non-human primates, the question remains unanswered for now. But the advent of more genomic data hold promise to tackle this issue. …
With the publication of ‘A History of Hybrids? Genomic Patterns of Introgression in the True Geese’ in BMC Evolutionary Biology, the three goose papers from my PhD thesis have made it into scientific journals. The trilogy is complete, but the story continues…
During my PhD, I studied the evolutionary history of the True Geese. This bird group contains about 17 species (depending on which authority you follow) and is traditionally divided into two genera: Anser and Branta. At the start of my PhD, I was surprised to find out that the phylogeny (i.e. evolutionary tree) of the geese was still unresolved. The failure to resolve the relationships between these bird species is probably due to high levels of hybridization. …
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