<< Chapter < Page Chapter >> Page >
Photo (a) shows a salmon swimming. Photo (b) shows pronghorn antelope running on a plain. Photo (c) shows chimpanzees.
The (a) Chinook salmon mates once and dies. The (b) pronghorn antelope mates during specific times of the year during its reproductive life. Primates, such as humans and (c) chimpanzees, may mate on any day, independent of ovulation. (credit a: modification of work by Roger Tabor, USFWS; credit b: modification of work by Mark Gocke, USDA; credit c: modification of work by “Shiny Things”/Flickr)

Play this interactive PBS evolution-based mating game to learn more about reproductive strategies.

Evolution connection

Energy budgets, reproductive costs, and sexual selection in Drosophila

Research into how animals allocate their energy resources for growth, maintenance, and reproduction has used a variety of experimental animal models. Some of this work has been done using the common fruit fly, Drosophila melanogaster . Studies have shown that not only does reproduction have a cost as far as how long male fruit flies live, but also fruit flies that have already mated several times have limited sperm remaining for reproduction. Fruit flies maximize their last chances at reproduction by selecting optimal mates.

In a 1981 study, male fruit flies were placed in enclosures with either virgin or inseminated females. The males that mated with virgin females had shorter life spans than those in contact with the same number of inseminated females with which they were unable to mate. This effect occurred regardless of how large (indicative of their age) the males were. Thus, males that did not mate lived longer, allowing them more opportunities to find mates in the future.

More recent studies, performed in 2006, show how males select the female with which they will mate and how this is affected by previous matings ( [link] ). Adapted from Phillip G. Byrne and William R. Rice, “Evidence for adaptive male mate choice in the fruit fly Drosophila melanogaster, ” Proc Biol Sci. 273, no. 1589 (2006): 917-922, doi: 10.1098/rspb.2005.3372. Males were allowed to select between smaller and larger females. Findings showed that larger females had greater fecundity, producing twice as many offspring per mating as the smaller females did. Males that had previously mated, and thus had lower supplies of sperm, were termed “resource-depleted,” while males that had not mated were termed “non-resource-depleted.” The study showed that although non-resource-depleted males preferentially mated with larger females, this selection of partners was more pronounced in the resource-depleted males. Thus, males with depleted sperm supplies, which were limited in the number of times that they could mate before they replenished their sperm supply, selected larger, more fecund females, thus maximizing their chances for offspring. This study was one of the first to show that the physiological state of the male affected its mating behavior in a way that clearly maximizes its use of limited reproductive resources.

Table compares the change in percentage of large versus small females mated for sperm-depleted males versus non-depleted males. Non-depleted males preferred large over small females by 8 percent. Sperm depleted males had a greater preference for large females: 15 percent. Error for both measurements was plus or minus 5 percent.
Male fruit flies that had previously mated (sperm-depleted) picked larger, more fecund females more often than those that had not mated (non-sperm-depleted). This change in behavior causes an increase in the efficiency of a limited reproductive resource: sperm.

These studies demonstrate two ways in which the energy budget is a factor in reproduction. First, energy expended on mating may reduce an animal’s lifespan, but by this time they have already reproduced, so in the context of natural selection this early death is not of much evolutionary importance. Second, when resources such as sperm (and the energy needed to replenish it) are low, an organism’s behavior can change to give them the best chance of passing their genes on to the next generation. These changes in behavior, so important to evolution, are studied in a discipline known as behavioral biology, or ethology, at the interface between population biology and psychology.

Section summary

All species have evolved a pattern of living, called a life history strategy, in which they partition energy for growth, maintenance, and reproduction. These patterns evolve through natural selection; they allow species to adapt to their environment to obtain the resources they need to successfully reproduce. There is an inverse relationship between fecundity and parental care. A species may reproduce early in life to ensure surviving to a reproductive age or reproduce later in life to become larger and healthier and better able to give parental care. A species may reproduce once (semelparity) or many times (iteroparity) in its life.

Questions & Answers

biology introduction
Khab Reply
state the main functions of the leaf
kalisto Reply
what is the similarity between meiosis and mitosis
kalisto
Regulation of blood sugar level
Kyara Reply
Describes larmack theory
Mayiik Reply
Mention five modes of nutrition in ecology
Mayiik
Saprophytic
Evans
what is biology
Imisi Reply
Biology is the study of life
Aisha
Yea
Mayiik
what is insulin and where is it found in the body
Cecilia Reply
An illustration of the negative feedback mechanism in homeostasis
Cecilia
How we know
Nhial
That is not the meaning
Mayiik
what are chromosomes
Ibrahim
factor that affect the diffusion of substance
Nwafor Reply
Explain the specialized functions of the organs involved in processing food in the body
Brah Reply
none
Emmanuel
Processing food involves ingestion eating, digestion mechanical and enzymatic breakdown of large molecules, absorption cellular uptake of nutrients, and elimination removal of undigested waste as feces. Many organs work together to digest food and absorb nutrients.
Timileyin
biology is the study of life
Evelyn Reply
introduction of biology
Alison Reply
what is biology
Alison
biology is the scientific study of life
Gloria
Biology is the study of science. living and non living things in our environment. that's biotics and abiotic components of life.
Oluwadare
what are limit factors of photosynthesis
Mpolokeng Reply
what are limit factors of photosynthesis
Friday
Light intensity Carbon dioxide Temperature
Timileyin
what is virus
Chidimmma
virus are said to be microscopic organisms that can't be seen with naked eyes. but With the aid of electron microscope.
Oluwadare
are they unicellular or multicellular
Samkelo
sunlight.. water Carbon dioxide glucose
Oluwadare
what is a cell
Veronica Reply
are building blocks of the body
Mercy
cell is a smalles unit of life
Joeflexy
Cell is the basic ,structural and functional unit of life
ANGELINA
cell is the microscopic unit makes up an organ
Lance
Cell is the basic, structural and functional unit of life.
Esther
why do phosphate group attaches to the protein?
Abel Reply
what are enzymes?
Reiah Reply
enzymes are chemical substances that speed up the rate of chemical reactions
Favour
yes it is still available
hashim
This are chemical compound that speed up the digestion of food
Mayiik
these are chemical substances that speed up the rate of reactions and remain the same at the end of the reaction
kalisto
why don't we have humans clones?
Mvelo Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Biology' conversation and receive update notifications?

Ask