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, even for tiny ocean animals such as ostracodes. With just a few exceptions to the rule, male sex cells must fertilize female sex cells to make offspring. While some animals, such as male and female clams, release sex cells into the water for chance encounters, 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 that make creative use of the senses, ranging 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 because females usually make the larger investment in creating and raising offspring, and so 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, driving a sort of evolutionary arms race to have the showiest feather plumage. Showier plumage may lead to more mating opportunities, which leads to more offspring, which 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, 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 the hypothesis 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 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 while answering 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 (8)
  • josiec-4-pla
    2/07/2017 - 05:26 p.m.

    This article is about scientists studying the different ways animals attract mates and how it can relate to natural selection. While animals need something flashy to attract a mate, the same feature could also attract predators making the animal easy prey. I found this article very interesting, because not only am I planning to go into Biology after I leave high school, but the irony of the situation is considerable. The same feature that is supposed to be attracting a mate to reproduce is the one leading them to their deathbed. If sexual selection were to be proven to play a role in extinction, it would raise the standards of "survival of the fittest" greatly. Animals would have to find the perfect medium between flamboyant and dull just to survive long enough to pass their genes down

  • meganl-7-pla
    2/08/2017 - 09:10 p.m.

    This article talked about how animals are evolving and how the changes to the animals might actually make them more susceptible to extinction. A main reason for animals to evolve is to help them through the process of finding a mate and reproducing. However, finding a mate can be difficult so changes like large, colorful feathers, big antlers, and "glow in the dark" features have been acquired through generations of looking for a mate. Despite the grand, attractive looks, the extent of the disadvantages may outweigh the advantages. For example, bigger antlers may make a deer slower, colorful feathers attract predators, and bioluminescence could attract a very hungry fish. Extreme cases of this type of evolution could even lead to an extinction of the species, all because of the desire for a mate. I connected with this article because I just finished a unit in biology about evolution and reproduction in animals. We never learned about sexual selection or its affect on animals species around the world, and I thing its quite interesting to see that animals are becoming more vulnerable to predators just to attract a mate.

  • kaileew-ste
    2/10/2017 - 11:27 a.m.

    When two mammals are mating, the female usually takes some convincing. If there is something wrong with a male that could attract competition then the female will not chose them. If no female choses this male, then they will go extinct. For example, a glowing jellyfish could attract predators so a female won't choose him, causing the glowing jellyfish to go extinct.

  • kadenk-ver
    2/10/2017 - 12:11 p.m.

    Because eviloution could hange them and when they mate the offspring could not develop right causeing to die ect......

  • zakrym-ste
    2/10/2017 - 01:44 p.m.

    This article was about the reproduction in the ocean. A male sex cell must fertilize a female sex cell. The offspring may not develop into adults.

  • johnz-pla
    2/14/2017 - 10:47 p.m.

    This article discussed how sexually selected traits lead to more reproduction but may be detrimental to the overall survivability of a species. Glowing deep sea animals are more visible to predators, and large antlers make an animal less nimble. This article connects to civic engagement by showing how scientific research can help inform the public about the environment. The more information people have the environment, the more they will understand and care about it. In this case, better understanding of how some species are endangered by their traits could motivate citizens to help prevent extinction of those species.

  • jacklynt-ste
    2/17/2017 - 02:27 p.m.

    Mate choice has a lot to do with extinction. If an animal stands out to predators, they will not be trusted by the opposite sex. If they do not reproduce, then that animal will go extinct.

  • noahr-ste
    2/20/2017 - 07:50 a.m.

    The issue is the male has to reproduce with the female which can cause issues if their so different. Also the offspring do not always grow to become a adult so they can keep producing.

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