Sunday, August 13, 2017

Climate Change Is Disrupting The Birds And Bees

We all know that climate change will cause more extreme weather and rising seas. But it is also having an unexpected effect on sex.

Some predatory birds are hatching after their prey, meaning they have less to eat (Credit: Alamy) Click to Enlarge.
Over the last two decades, scientists have found that warmer temperatures are quietly spoiling the mood, making it harder for plants and animals to reproduce.

Here are five ways that climate change is ruining sex lives.

It’s a numbers game
While humans and many other animals determine sex genetically, many reptiles and some fish use the incubation temperature of the eggs to set the gender of their offspring.  This means that changing global temperatures could alter the ratio of sexes produced, making it harder for these animals to find mates.
Timing is everything
Phenological shifts are common, because many animals use environmental cues like temperature and rainfall to time key events like migration, flowering and breeding.  Climate change is changing the timing and strength of the seasons, and as these cues change, the annual ebb and flow of the natural world is being disrupted.

In fact, one of the first pieces of evidence for the effect of climate change on living things was the discovery that plants are flowering earlier and earlier each year.  In 2002 a landmark study showed that 385 British plant species were flowering on average 4.5 days earlier than in the 1990s.  The same story is playing out across the globe: a 2008 meta-analysis looked at 650 temperate plant species in Europe, Asia and North America, and found that spring flowering had advanced by 1.9 days per decade on average.

The biggest concern is that plants and their pollinators might respond differently to climate change, leading to a mismatch that could significantly affect plant reproduction.  For instance, in Japan the flowering of the plant Corydalis ambigua has advanced faster than the emergence of its bumblebee pollinators, resulting in a mismatch that reduces seed production in years with an early spring.  Such mismatches could have a major impact on certain crop plants.

Happily, a 2011 study found that most plants and pollinators are responding to climate change in a similar way, maintaining their synchrony despite large changes in temperature.
Bending the rules of attraction
Changing environmental cues might also influence how animals court members of the opposite sex.

The decorations, displays, dances, and songs that animals use to attract a mate are all heavily dependent on the environmental conditions the animal lives in.  That is why they became attractive in the first place, says Carlos Botero of Washington University in Saint Louis.
Across the animal kingdom, lavish looks and elaborate displays act as honest signals of the quality of a mate, helping females to choose the right parent to give their offspring the best genetic start in life.

But environmental changes can break the link between appearance and quality.
A mate for life?
Warmer climates seem to have a tendency to make animals less faithful.  In a 2012 study, Botero studied monogamy in 122 species of bird.  He found that “in places where environments change more frequently and unexpectedly, apparently monogamous females tend to hedge their bets by mating with more than one partner on the side”.

These “extra-pair relationships” become increasingly frequent as annual climatic cycles become more variable.  Female birds “are also more likely to terminate bonds with partners that are no longer yielding the benefits they expected”, says Botero.  He argues that these “divorces” and “affairs” may become more common as the climate becomes less predictable.

Read more at Climate Change Is Disrupting The Birds And Bees

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