hybrid future? Hybridization could make heat-averse species more resistant to climate change

With the climate warming rapidly, many species will struggle to avoid extinction. If they have time, they can evolve to the new environmental conditions. But they don’t. This is where crossbreeding can help. When related species reproduce, an influx of new genetic diversity can help them adapt to warmer environments.

Hybridization is often a cause for concern for the conservation of species. our New search He suggests that genetic mixing across species may actually provide better chances of survival for some species—particularly those that are less tolerant of environmental changes and are likely to be hardest hit by a hotter climate.

Some species won’t have to face an utterly ambiguous future on their own. Related species may be able to help.

We looked at what happened when warm- and cold-adapted rainbowfish mated. We found the new welcome leak Genetic diversity It was a boon, reducing the risk of extinction for threatened species and potentially making them more resilient.

Upland rainbowfish are less well-adapted to warmer waters—but hybrid rainbowfish do best.
Diana Elena Fornico

what did we learn?

Australia humid tropics It ran roughly from Townsville to Cooktown, including the Daintree Rainforest. Unfortunately, this amazing biome is expected to be hit hard by climate change. The cold climates of mountain rainforests are likely to disappear.

Many species of tropical rainbow fish live in the rivers here (Melanotaenia spp.). Some species live in cooler waters, higher in headwaters. Others live in warmer waters further down, but move slowly up rivers as the climate warms. Different types of rainbow fish can easily breed.

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We collected samples from five species of rainbowfish that are adapted to life at different altitudes. This included a widespread lowland species known for its adaptability, as well as three species only able to live in the narrow range of mountain rivers and one only able to live in the lower reaches.

Using genomic analyses, we found a mixture of pure and mixed populations of these species of rainbow fish. Next, we found the genes that enable rainbowfish to adapt to the changing climates of the region and estimated how vulnerable each species would be to future climate.

Rainbow Australia

A species of rainbow fish that we have collected from the wet tropics of Australia.
Keith MartinAnd Author introduced

What did we find? that cold-water rainbowfish species were in a better position to adapt to future climates if they crossed with general warm-water species.

We then modeled the available habitats of cold-water species against the warming expected in climate models. We found that upland rainbowfish species probably lose more than 90% of their habitat within 50 years, while warm-water, lowland species will lose relatively little habitat.

If upland species are to survive, they must either find new habitats or adapt to new conditions. Of course, freshwater fish are very limited in their ability to find a new home. These rainbow fish, in particular, live in the last remaining cool tropical cloud forests in Australia. Even if we wanted to move them, there weren’t many places they could go.

The only other option is adaptation On site.

Fortunately for the rainbow fish—and perhaps many other species—we found that warm- and cold-type hybrid fish had greater genetic diversity. This was particularly true for genes associated with the ability to live in warmer conditions.

These hybrids also do not require as much general genetic alteration to keep up with climate change compared to pure populations. Taken together, this means we could be witnessing a kind of natural evolutionary rescue, which may help mitigate the impact of climate change.

They will need every little help they can get to escape the hot water they will find themselves in. Our climate models indicate that populations of purebred rainbowfish will need to evolve much faster in the coming decades than they have since the arrival of the Holocene epoch around 11,000 years ago.

Current of the humid tropics

Many species have very limited ranges, such as the rainbow fish which only lives in cooler currents in the humid tropics.
Michael HammerAnd Author introduced

How can crossbreeding help?

Genetic diversity is one of the best resources a species can have. Food, water, and shelter are immediately important to individual animals. But genes are also important from a bird’s eye view.

When a species has wide genetic diversity, it is in a much better position to weather changes. If their environment changes, they have a better chance of evolving to deal with the new conditions.

This is especially important now, as millions of species face the existential threat of climate change. If they have enough time to adjust, they can adapt. But this happens at warp speed. Species that cannot handle the great variability in their environment are at greater risk of extinction because they often lack the genetic diversity to adapt to climate change.

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When you think of genetic diversity, you might think of a large population of one species. But in reality, genes can jump across species.

This means that both crossbreeding and mixing between populations (through migration) or between species (crossbreeding) could enable some threatened species to get welcome boosts of new genetic diversity from species that have already adapted to warmer environments.

Hybrids are often seen as problematic.

There’s an old adage in conservation: “Local is best.” By this, scientists mean that local, often small populations are best managed in isolation to preserve the genetic purity of the lineages. But more and more we realized that this doctrine can do more harm than good.

Hybrid populations have often been overlooked—or even thought of as threatening the gene pool of endangered species.

What we hope our research will show is that hybridization may contribute to the survival of some species.

Of course, mixing with other species may not always lead to the same result. We need to know when crossbreeding can be beneficial for conservation.

We hope that this work will provide rare empirical support for the idea that genetic admixture is not always a threat. In fact, it may hold promise for a new tool for conservation.

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