Scandal, promiscuity, and…true love?

When looking at the mating rituals of some animals, the behaviours can often seem scandalous, gross, or just plain odd to us. But what really is ‘normal’ behaviour? Because when it comes to the animal kingdom, anything goes.

This month a study published by the University of Oxford, found that female fruit flies will mate with a male, and then move on to mating with its brothers – something that I’m sure would be worthy of a great Jeremy Kyle episode! The study aimed to look at the mating behaviours of the fruit fly by taking an individual and giving it an option of two mates. Once the choice was made and the deed done, the scientists would then give the same fruit fly a new set of choices to mate with; a suitor from the same family as their previous mate, or a suitor with no relation to their previous mate.

Queensland_Fruit_Fly_-_Bactrocera_tryoni

A Queensland fruit fly

The scientists interestingly found that the males and females had completely different approaches to the mating game. The males tended to choose the mysterious, new mate presented to them each time, rather than keeping it in the family and mating with essentially their ‘sister-in-law’. However, females showed the opposite response. Why this occurs is still a bit of a mystery but imagine if the same occurred in humans! We would have far more bust ups between brothers on our hands.

Promiscuity in the animal kingdom is common, with the majority of individuals moving from mate to mate, or sleeping with many mates at one time. For example in elephant seals, the dominant male of the group will impregnate up to 50 females in one breeding season. Although this is a reward I think they deserve after fighting so intently to gain these privileges. The great David Attenborough explains below:

However, there are still many examples of species that show behaviour similar to humans and ‘mate for life’*. In fact, a study published this month from the University of Pennsylvania showed that owl monkeys do not cheat on their partners – something even us humans can’t vouch for.

The scientists took 17 owl monkey couples and carried out a paternity test on their offspring to check genetically who their fathers were. The results of the genetic tests revealed that every owl monkey had actually been completely faithful to its partner. Dr. Fernandez-Duque who has been studying the couples for 18 years, explained “In the 18 years…we never witnessed a little sneaky copulation with a neighbour, or that one partner that dashed off for some time. So in that sense we were not very much surprised by our results. But true genetic monogamy is very rare. We would not have been surprised if there had been at least one non-pair infant, but there were none.”

The scientists have put this rare mating behaviour down to the way in which males care for their offspring. Often in the animal kingdom the females are the primary carers of offspring and the fathers show very little parental care behaviour. But this is not the case in the owl monkey, where the fathers regularly carry their children on their bodies, play with them and feed them. The scientists explain that by carrying out these parental duties and sharing the work load between the mother and father, the couple spend much more time together and this leads to the monogamy observed.

Let me know what you think about the two very different studies discussed today – comment below!

* Contrary to popular belief, lobsters do not actually mate for life. So Phoebe is actually scientifically incorrect when she tells Ross on Friends that Rachel is his lobster. Lobsters are actually pretty promiscuous little things, but then again Ross and Rachel did end up together so what does it matter in the end!

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(#1) Let’s Talk About…What would you give up for a tiger?

Would you give up your house? Because some people would.

This is the first of my weekly ‘Let’s Talk About…’ posts in which we shall be discussing the topics that matter in conservation and environmental biology. First up: what would you give up to save a species from extinction? And which species are the most important to save?

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In light of the announcement last week that three new Sumatran tiger cubs have been born in London zoo (so adorable!), I came across this article by ScienceDaily which really got me thinking. The article sums up research carried out by the University of Kent in which scientists have found communities in India that are willing to give up their homes and be relocated to new areas to help protect the wild tiger populations that live in the local area. Each household in these communities were asked to fill out a survey and the researchers found that there was an overwhelmingly positive response to being relocated to protect the tigers.

In order to thrive tigers, as large, solitary animals, require a lot of space to have access to enough food and breeding refuges. However tigers are found in South Asia where the human populations of these countries are increasing at an extraordinary rate. This means that the forests in which these tigers reside are increasingly being converted into housing and farmland for human use. When this occurs the land becomes fragmented (a process known as habitat fragmentation) isolating populations of tigers in smaller and smaller regions of forest.

As the fragments of habitat shrink, the number of tigers the habitat can support decreases and so sadly, population numbers decrease. Scientists have shown that by relocating these human populations in India, we can decrease the fragmentation of the forest we are causing and reduce our impact on the tiger populations.

Here is a diagram I created to explain habitat fragmentation (I apologise for my dodgy diagram drawing skills here but I think it will get the point across). In picture A, the area inhabited by tigers (the bits in colour) are very fragmented across the whole area of white space representing the land that was once forest. In the study discussed above, by relocating communities the land becomes less fragmented and there are less small, isolated tiger habitat that are likely to lead to extinctions.

Here is a diagram I created to so you can see the effect of habitat fragmentation. In picture A, the area inhabited by tigers (the bits in colour) are very fragmented across the area of white space (the area now inhabited by humans). In the study discussed above, by relocating communities in picture B, the land becomes less fragmented and there are less small, isolated habitat fragments that are likely to lead to tiger extinctions.

So the discussion today is would you relocate your home to protect these endangered creatures? Now to be fair to everyone, I must explain that the Indian communities studied here would benefit somewhat from relocation with better access to education and health facilities, but nonetheless I think this is a fascinating discussion to be had. And leading on from that, would your answer change if instead of protecting tigers, we we’re discussing wild deer or rabbits?

Moving home is a rather large sacrifice so let’s look at something a bit smaller. I read in the news this week about Richmond Road in London being shut off to motorists for the fourth year in a row. The reason? To conserve the local toad populations.

By closing off the road for two weeks, the toads can safely cross over the road to a popular breeding pond in which they can all get jiggy with it and reproduce, ensuring that the local populations stay at a stable level. However this sacrifice has not gone down well with the some of the local residents, and I can’t say that I blame them. If I lived near that road I would probably find a bit of a pain too. But again, what if we weren’t talking about toads? What if we we’re talking about wild rabbits or deer? I’d predict that people would take more lightly to the road being shut off.

And so we come to one of the challenges of conservation projects globally; which species are more important to conserve? The adorable tigers and pandas of the world that we enjoy looking at? Or is how we perceive certain species based on aesthetics jading our judgement? Are there in fact more important species out there that carry out functions that human communities or whole ecosystems rely on, that we should really be focusing our efforts on?

Let’s get a discussion going in the comments below. I’d love to know what you think of this topic. There are no right or wrong answers!
Also vote below!

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Is it a boy? Is it a girl?… It’s both

“The truth about Finding Nemo unveiled!” and similar headlines have been circulating the internet for a while now. If you don’t know the story have a little read here but to sum it up, scientists have pointed out that if Nemo’s mother died in real life, his father would actually turn into a female to replace his mother, and then Nemo would become his (newly-female) father’s sexual partner. Not the story I think Disney originally wanted to tell!

In fact, all clownfish are born as male and at any point in their lifetime can change their gender from male to female to ensure that there are always enough females in the population to mate with.

Ocellaris_clownfish,_Flickr

But clownfish are not the only species on the planet that can change gender. Organisms that change sex during their lifetime are known as sequential hermaphrodites, and there are many examples of these across the animal kingdom. Sequential hermaphroditism is common in plants, snails, slugs, worms and fish. Species of wrasse fish for example, can do the opposite to Nemo, with females at the end of their lifetime showing the ability to change to male.

As biologists we love to give everything a name so let me fill you in on the lingo: when males turn into females (like the clownfish) this process is known as protandry, and when females turn into males (like the wrasse fish), we call this protogyny.

Going back to the movies theme, you may recall another example of sequential hermaphroditism hiding in Jurassic Park when Dr. Grant discovers that the supposedly all female dinosaurs in the park are mysteriously breeding. The explanation given in the film is that the scientists used frog DNA to fill in the missing gaps of the recovered dinosaur genomes (the complete genetic material needed to create an individual). The scientists in the movie used DNA from the common frog (Rana temporaria) and in the wild the females of this frog species have been shown to spontaneously change gender to male. And so in the movie the frog DNA incorporated into the dinosaurs gives them the ability to change to a male gender, and eureka the mystery is solved!

But why do all these organisms change gender in the first place? Scientists believe this phenomenon first evolved due to the way in which these species chose their sexual partners. In protogyny hermarphrodite species the largest males are the most attractive to females. But it takes time to grow and become large and attractive. Individuals that are born female can therefore mate and reproduce until they grow big enough that they would attract themselves given the chance and switch gender. This means that during their lifetime they can see the experience of mating from both sides of the partnership. Pretty weird huh?

In protandry hermaphrodite species, as females age the number of eggs they can produce in one sitting increases. By being able to change gender during their lifetime, in both protogyny and protoandry species it allows individuals to get the best of both worlds; to be a male or a female when the time is right to maximise their reproductive ability. And so this is another fine example of evolution, which works to maximise your ability to pass on your genes to the next generation. Greater reproductive ability = more offspring (and so more of your genes left in the world when you die).

So sequential hermaphroditism; a pretty wacky, but incredibly clever way of getting more action.

Let me know what you think about this fascinating phenomenon in the comments below!

If you found this interesting, this article by National Geographic is a really great piece on a topic very similar; how organisms can ‘dress up’ as the opposite sex. Take a look!

Posted in Animal behaviour | Tagged , , , | 3 Comments

The coolest critters on the block

A rat that may hold the cure for cancer AND has a monarchy; it can only be the naked mole rat.

When the idea of this blog came about to explore the peculiar creatures and behaviours of the animal kingdom, one particular species came to mind instantly; the naked mole rat. If you’ve never heard about these odd but incredible East African rodents prepare to have your mind blown!

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Now let’s address the obvious; these creatures are not pretty things. With their wrinkly, hairless skin and large, jutting-out teeth, the naked mole rat is unlikely to be winning beauty contests any time soon. However over the last year I have learnt some fascinating things about these small creatures that I think make these critters some of the coolest around.

“Could mole rats hold the key to a cure for cancer? Scientists hail ‘potentially life-changing’ breakthrough” Daily Mail
“Naked mole-rat gives cancer clues” BBC News
A cure for ALL cancers is on the way as scientists make major breakthrough” Daily Express

These are just some of the headlines from the media over the last six months regarding the naked mole rat. So is it true? Have we finally found the secret to the long awaited cure for cancer? Are all the #nomakeupselfies that have been gracing our Facebook feeds for the last week for nothing?

Well not quite. It has long been known that the naked mole rat can live for up to 30 years, an extremely long time compared to other rodents of the same size. In fact if humans were to live as long as naked mole rats determined by our body size, we would live for an impressive 600 years! One of the many reasons for the longevity of these rats lies in their immunity to cancer.

Last year the University of Rochester explored the solutions the naked mole rat uses to overcome this widespread killer. The team of scientists found a substance that appears in the cells of all animals (including us) called hyaluronan, that was different from any hyaluronan seen before. When the team removed this from the cells of naked mole rats, they found that these individuals then became susceptible to cancer, suggesting hyaluronan is the key to overcoming cancer. Well, key to overcoming cancer in naked mole rats at least.

So hyaluronan was the culprit for all the rumours and headlines, and actually led to these creatures being named Science magazine’s Vertebrate of the Year 2013. But will this new found understanding of hyaluronan help us find the elusive cure we have tried so hard to find? Only time will tell.

One of the coolest things I think naked mole rats show us is the amazing things we can achieve when we all work together as one big, harmonious, happy family.

The naked mole rat is the only mammal in the animal kingdom that demonstrates a behaviour known as eusociality (when individuals all work together as a unit to achieve day-to-day tasks). However this behaviour is common in insects and an example that you’ll probably be most familiar with is in bees. In bee colonies there is a queen bee that rules over all the other bees, and the same system occurs in naked mole rat colonies. There is one female queen that is in charge of a colony of up to 100 individuals. The queen selects a few males that she will breed with and the rest of the colony are either assigned roles as workers, who dig for roots and tubers to feed the colony and maintain the complex network of tunnels in which the colony lives, or as soldiers, who protect the colony against snake predators that occasionally slither into these tunnels.

Although this social structure may seem odd, this kind of organisation allows eusocial creatures to be extremely efficient and the results of this efficiency can often be impressive. Below is a video where a team have poured concrete into eusocial ant tunnels and then dug down into the ground around the set concrete to reveal something that can only be described as incredible!

I have watched this video many times over the years and it never fails to amaze me. I guess the equivalent of us creating this kind of remarkable structure is when the Egyptians created the pyramids, not something us humans can pull off often!

Naked mole rats also dig complex tunnels in a manner similar to the ants in the video, and in a year, typically a colony will build a network of tunnels approximately 3km in length. To put that in perspective, 3km is the distance of my walk home from university which takes me 40 minutes to do. Imagine a 40 minute walk in tunnel form. Pretty impressive huh?

So there we have it, my low down on these wonderful creatures, proving that there are more important things in life than looks.

Let me know below what you think of these creatures. Have I managed to convince you of their wonder?
Comment below!

 

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