What does mate choice have to do with extinction? Can you see any differences between these millimeter-long male and female ostracodes (tiny ocean animals)? Microscope photos of fossil ostracodes. (Bottom, left) In this species of tiny animal called an ostracod, males are smaller than females and have special light organs that they use to compete for females by emitting flashes of bioluminesence. (Gene Hunt, Smithsonian/Jim G. Morin)
What does mate choice have to do with extinction?
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In the animal kingdom, sexual reproduction is the rule. This is even true for tiny ocean animals. One example is ostracodes. With just a few exceptions to the rule, male sex cells must fertilize female sex cells. That is how they make offspring. Some animals, such as male and female clams, release sex cells into the water for chance encounters. But reproduction in many animals requires that males and females find each other. 
 
Attracting individuals of the same species is achieved in a startling variety of ways. They can make creative use of the senses. This activity can range from singing by frogs to dancing by jumping spiders to luminescing by deep-sea animals. Once found, a potential mate may need to be convinced to go forward with the mating relationship. Generally, it's the male doing the convincing. This is because females usually make the larger investment in creating and raising offspring. So females are choosier about who to mate with.
 
Let's take birds as an example. In birds, males invite females to their territories by singing, sporting bright feathers and doing courtship dances. The more flamboyant males tend to be more successful at attracting females. This activity by males drives a sort of evolutionary arms race. Which one can have the showiest feather plumage? Showier plumage may lead to more mating opportunities. This leads to more offspring. That perpetuates showier plumage in the population of birds.
 
This form of natural selection driven by mate choice is called "sexual selection." While it has inspired spectacular characteristics in animals, from feathers to antlers to lion manes, it might have a dark side. Peacocks with larger tails may be easier for wild dogs to catch, for example. Elks with larger antlers might not be as agile against wolf attacks. And a lit-up squid might attract a hungry fish instead of a mate. Species with more extreme differences between males and females ("sexual dimorphism") might be more susceptible to extinction in the long run.
 
Smithsonian paleontologist Dr. Gene Hunt is using tiny ocean ostracodes as a model to examine a hypothesis. It is that sexual selection plays a role in extinction. Learn more about what his studies of ostracodes are revealing in a live "Smithsonian Science How" webcast. It airs on Thursday, Feb. 9. In "What Tiny Marine Fossils Reveal about Extinction" (airs at 11 a.m. and 2 p.m. EST on the Q?rius website), Gene will show you how he tests hypotheses. He also will answer your questions live. You can also get teaching resources to use with the webcast.

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CRITICAL THINKING QUESTION
How might species with more extreme differences between males and females be more susceptible to extinction?
Write your answers in the comments section below


COMMENTS (25)
  • zaneh-jon
    2/12/2017 - 09:25 a.m.

    The article's topic is rather interesting but I was expecting more about the topic than there actually is. However, it is nice to learn about animal mating and I'd like to hear more on how it affects extinction.

  • irisp-ste
    2/13/2017 - 09:16 a.m.

    For species with extreme differences, males and females may have a more difficult time being in the same habitats at the same time to reproduce and boost the population. If the two animals struggle to find each other because they are not typically in the same environment, the males and females will only die off while never producing anymore offspring to prevent extinction.

  • jacoba-kul
    2/13/2017 - 12:04 p.m.

    It's a natural process with evolution. The proper choice could mean the survival of the species and the wrong choice will lead to the extinction

    • aleahs-kul
      2/14/2017 - 10:10 a.m.

      I agree with Jacob, that if choosing the wrong option could lead to extinction. Evolution is natural and occurs to animals so they develop to who and what they become.(30 words)

  • neaves-bur
    2/13/2017 - 12:58 p.m.

    The species with more extreme differences between male and female species will make them more susceptible to extinction because they might not recognize each other as being the same species and never mate. :(

    This made me very curious and now I'm thinking: what if a certain species is actually a species that we know about already and just looks different? How much would that change our outlook on nature?

  • allisons-kul
    2/13/2017 - 01:50 p.m.

    I had heard about some of this before, such as birds showing their feathers and dancing trying to attract a female mate. I feel like this is sort of like the world today. Girls create standards and have a certain "bar" to which boys have to either reach or be better than to get the opportunity to go on a date or be in a relationship with the girl. It seems to always be the male that is trying to impress the female.

    • taylorm-kul
      2/17/2017 - 10:12 a.m.

      I agree, because you don't see the girl out there trying to impress the boy. It's not common for it to work out that way anyway.

  • lukeh-orv
    2/13/2017 - 02:38 p.m.

    I had heard about some of this before, such as birds showing their feathers and dancing trying to attract a female mate. I feel like this is sort of like the world today. Girls create standards and have a certain "bar" to which boys have to either reach or be better than to get the opportunity to go on a date or be in a relationship with the girl. It seems to always be the male that is trying to impress the female.

  • aleahs-kul
    2/14/2017 - 10:06 a.m.

    This study is super interesting I think, because it shows how different species of animals mate and what they are interested in. Each species have a different way of finding a mate, and all are very unique. This would definitely be an interesting job to study mating I think, but I wouldn’t ever be interested in doing it myself.(59 words)

  • rileyn-kul
    2/15/2017 - 12:54 p.m.

    I find this the same as when a bull and cow, or a sow and a boar mate. There are attractive bulls that cows like and there are not attractive bulls that the cows wont "flirt up to".

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