Lemur evolution happened in waves, not a single burst

Lemurs didn’t spring from a single explosive radiation after reaching Madagascar. Instead, their extraordinary variety arose through multiple waves of speciation, some as recent as the middle to late Pleistocene about 500,000 years ago. 

Interbreeding between species also played a creative role, feeding genetic novelty into lineages that later split again.

Lemur evolution in Madagascar

An international team led by the German Primate Center – Leibniz Institute for Primate Research (DPZ) reports these findings in new research on Madagascar’s primates. 

Lemurs comprise more than 15 percent of today’s living primate species even though their island home covers less than one percent of Earth’s land. The study challenges a popular island narrative: that a single early radiation explains most living diversity.

Lemurs are strepsirrhines, an ancient primate branch that diverged from the haplorrhines – monkeys, apes, and humans – over 70 million years ago. 

Their ancestors likely rafted to Madagascar roughly 53 million years ago and then adapted to a striking range of habitats, from humid rainforests to dry spiny thickets, coastal scrub, and mountains. 

Today, scientists recognize more than 100 species, with at least 16 more lost in just the past two millennia of human presence.

Multiple bursts, not one

The team analyzed genomic data from 79 lemur species spanning the island’s main genera. Their phylogenetic reconstructions revealed a major uptick in speciation about five to six million years ago, long after the earliest lemur radiations. 

The surge centered on three genera that dominate modern diversity: mouse lemurs (Microcebus), true lemurs (Eulemur), and sportive lemurs (Lepilemur). Rather than evidence of a single ancient “big bang,” the pattern points to repeated pulses of diversification layered across deep time.

The late burst surprised the researchers. In many groups, speciation rates peak early and then slow as ecological space fills.

Mouse lemurs, true lemurs, and sportive lemurs bucked that expectation. They kept minting new species into the late Neogene and Pleistocene while also swapping genes across species boundaries within their genera.

Hybridization as an engine of novelty

The genomic signal of gene flow was clear. Species in the same genus sometimes interbred and produced hybrids, and those hybrids were not evolutionary dead ends.

In several clades, hybrid-origin species were even more common than “classic” species formed solely by lineage splitting.

“Our analyses show that lemurs split into new species much more frequently than their closest relatives, the lorises in Africa and Asia,” explained Dietmar Zinner, a primate researcher in the Cognitive Ethology Laboratory at DPZ. 

“We were also able to show that genetic exchange, i.e. hybridization between species, was an important driver of this diversity.”

Complex conditions of Madagascar

Zinner conducted the work with colleagues Peter Kappeler from the Behavioral Ecology and Sociobiology Unit and Christian Roos from the Primate Genetics Laboratory.

On average, lemurs produced about 0.44 new species per million years across the tree, compared with only 0.15 per million years in lorises. In some groups, hybrid species outnumbered divergence-only species by a factor of four. 

That contrast demonstrates how Madagascar’s complex landscapes and shifting climates likely promoted both isolation and secondary contact, fueling cycles of split, mix, and split again.

Why lemurs outpaced lorises

Lorises, spread across Africa and Asia, share ancient ancestry with lemurs yet evolved under different ecological rules. 

Madagascar’s isolation, its mosaic of microclimates, and repeated environmental swings may have carved and rejoined populations in ways that favored diversification. 

Small-bodied lineages such as mouse lemurs, with short generation times, could respond rapidly to new ecological opportunities or barriers. When range edges met again, occasional interbreeding would have injected novel combinations of genes that selection could act upon, speeding the emergence of distinct forms.

The study’s timeline reaches into the middle and late Pleistocene. That means the island’s living diversity is not just a relic of distant Eocene events but a product of more recent evolutionary churn. 

Even relatively young climatic oscillations could have opened and closed corridors, fostering the repeated radiations now written into lemur genomes.

Conservation message written in genes

The results carry immediate implications for conservation. Roughly 95 percent of lemur species are threatened as forests shrink and climate extremes intensify. 

Hybridization can be a source of diversity, but it can also erode distinctive lineages if human-driven habitat change forces species into unnaturally high contact.

“In the future, conservation concepts must also take genetic diversity and the role of hybridization into account,” Zinner said.

That means protecting not just species names but the evolutionary processes that generated them. Safeguarding intact, connected habitats across environmental gradients will help maintain opportunities for natural diversification while limiting risky, human-triggered genetic swamping. 

Moreover, genetic monitoring is also needed alongside field surveys to understand where boundaries are stable, porous, or shifting under pressure.

The future of lemur evolution

“Nevertheless, this is not a license to neglect species conservation,” Roos said. “Without protective measures, many of the lemur species will go extinct before they can make use of this potential.”

For researchers, the next steps are clear. More high-resolution genomic work is needed to pinpoint when and where hybridization shaped lineages, which environmental factors promoted it, and how often it produced adaptive breakthroughs.

That knowledge can guide strategies that respect natural evolutionary dynamics while preventing unintended outcomes.

“The more we know about their evolutionary history and genetic diversity, the better we can secure their future,” Roos concluded.

Madagascar’s lemurs are a testament to what isolated landscapes and restless climates can sculpt. Their genomes show that evolution doesn’t always proceed in a single burst; sometimes it occurs in waves. 

Protecting those waves – and the forests that make them possible – will determine whether this extraordinary experiment continues.

The study is published in the journal Nature Communications. 

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