recap

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42.1 recap

Many species of animals, especially invertebrates, can reproduce asexually through budding, regeneration, or parthenogenesis. Asexual reproduction is an efficient use of resources but does not produce genetic diversity.

learning outcomes

You should be able to:

  • Describe circumstances that make asexual reproduction disadvantageous.

  • Describe the characteristics of the different types of asexual reproduction.

  • Explain conditions that would favor parthenogenesis over other forms of asexual reproduction.

Question 1

What is similar about budding and regeneration but not parthenogenesis?

Budding and regeneration begin with somatic (body) cells of the parent, whereas parthenogenesis begins with a germ (sex) cell, an egg that is not fertilized.

Question 2

Is global climate change likely to have a more negative impact on a species that reproduces asexually or one that reproduces sexually?

Global climate change is more likely to have a negative impact on asexually reproducing species, because they have less genetic variability to facilitate the evolution of adaptive changes that meet the new challenges imposed by climate change.

Question 3

The Komodo dragon is a very large, sexually breeding species of lizard that lives on the Indonesian island of Komodo. A young Komodo dragon named Flora was raised alone for many years in the London Zoo. One year after reaching sexual maturity, she laid a clutch of eggs that produced several baby dragons, all males. How did Flora reproduce? What advantage might this ability have for an island-dwelling species? Why is it significant that the offspring were all male?

Flora must have reproduced through parthenogenesis, an ability that would be adaptive for an island-dwelling species should a weather event eliminate all potential mates or cause a female to be relocated to another island with no potential mate. If the offspring of a parthenogenic reproductive event are male, they would be able to mate with their mother to initiate a new population of sexually reproducing individuals.

Asexual reproduction is an efficient way to use resources. Since most animals reproduce sexually, however, the genetic diversity produced by sexual reproduction must confer a tremendous advantage.