Accessibility/Mobile Features
Skip Navigation
Skip to Content
Editorial News
Lifestyles
Classified Sites

The Canadian Press - ONLINE EDITION

Number and size of animal offspring depends on parental support: study

VANCOUVER - A British Columbia researcher had to put herself in the position of a stock market investment analyst to solve a puzzle over why some animals have a few large babies while others have many small offspring.

The study, published Tuesday in the journal Proceedings of The Royal Society B: Biological Sciences, uses a math model similar to one that economists apply to analyse investment strategies to suggest the offspring question depends on the animal's partner.

Author Holly Kindsvater says the research has shown that if males are helping to raise the young, it's better to have many babies of a smaller size. But if the male is a lousy mate, then the female is better off having just a few large babies.

In nature — and as is observed in many school playgrounds — offspring that are born bigger usually have a greater chance of survival because they can compete better against others, says Kindsvater.

So in most cases in nature, a female animal with a desirable, robust mate that helps look after the young would give birth to a few large babies in order to pass on the good genes, the report says.

The assumption is "females should just make large babies when she has a really good mate because those babies are going to be so much more successful," says Kindsvater, a research scientist with Simon Fraser University's biological sciences department.

But she adds that researchers have observed female birds and fish producing large offspring after mating with a "bad" male — that is, one that slacks on parental care.

On the other hand, there are also females that mate with "good" males — those that bring back food and tend the nest — and then give birth to a bunch of smaller babies.

"That was very confusing for people," says Kindsvater. "In a way, it's saying you should invest more in the crappy stock, and it doesn't necessarily make sense."

The confusion cleared up once Kindsvater examined the reproductive patterns using the mathematical model similar to ones used by economists to determine investment strategies.

"We basically recognized that this ultimately is an investment problem and it's going to depend on the male contributions to offspring fitness," she said.

"Once you have insight that females need to invest according to how the males are going to improve her fitness or the offspring's fitness, you can kind of make sense of some of this variation."

Kindsvater's theory is that some fish and birds have evolved in such a way that reproductive efforts have become based on whether a female can maximize her "returns on investment."

Kindsvater says in the animal world, giving birth to many smaller babies takes less effort than giving birth to just a few large babies.

"Our model showed that when males are actually helping offspring grow faster, females can get away with investing less," she said.

"They can make smaller babies with these good males because these good males will help these babies do just as well."

And if a male is not going to stick around to take care of the offspring, it makes more sense for a female to "invest in" only a few big babies, since they would have a greater chance of surviving without the care of a father, she explains.

The study suggests that a female may not always get the mate that she wants — that is a fact of life, says Kindsvater.

But she can at least make the most of the situation by making sure her offspring prosper.

"What we previously might have thought was a mistake could actually still be the best reproductive strategy for that female," Kindsvater said.

  • Rate this Rate This Star Icon
  • This article has not yet been rated.
  • We want you to tell us what you think of our articles. If the story moves you, compels you to act or tells you something you didn’t know, mark it high. If you thought it was well written, do the same. If it doesn’t meet your standards, mark it accordingly.

    You can also register and/or login to the site and join the conversation by leaving a comment.

    Rate it yourself by rolling over the stars and clicking when you reach your desired rating. We want you to tell us what you think of our articles. If the story moves you, compels you to act or tells you something you didn’t know, mark it high.

Sort by: Newest to Oldest | Oldest to Newest | Most Popular 0 Commentscomment icon

You can comment on most stories on brandonsun.com. You can also agree or disagree with other comments. All you need to do is register and/or login and you can join the conversation and give your feedback.

There are no comments at the moment. Be the first to post a comment below.

Post Your Commentcomment icon

Comment
  • You have characters left

The Brandon Sun does not necessarily endorse any of the views posted. Comments are moderated before publication. By submitting your comment, you agree to our Terms and Conditions. New to commenting? Check out our Frequently Asked Questions.

letters

Make text: Larger | Smaller

Brandon Sun Business Directory
Submit a Random Act of Kindness
Why Not Minot?
Welcome to Winnipeg

Social Media