Ch. 22.1 The Origin of Species

Question 1

Speciation

Answer 1

• The “mystery of mysteries”
• The process by which one species splits into two species.
• Produces tremendous diversity of life, repeatedly yielding new species that differ from existing ones.
• Helps to explain the many features that organisms share; the “unity of life” When one species splits into two, the species that result share many characteristics because they are descended from this common ancestor
• Forms a conceptual bridge between microevolution and macroevolution

Question 2

Microevolution

Answer 2

Changes over time in allele frequencies in a population

Question 3

Macroevolution

Answer 3

The broad pattern of evolution above the species level

Ex. the origin of new groups of organisms such as mammals or flowering plants , through a series of speciation events

Question 4

Gene flow

Answer 4

The transfer of alleles between populations.
Typically occurs between the different populations of a species.
This ongoing exchange of alleles hold the populations together genetically

Question 5

Biological Species Concept

Answer 5

According to this concept, a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring - but do not produce viable, fertile offspring with members of other such groups.

Question 6

Reproductive Isolation

Answer 6

The existence of biological factors (barriers) that impede members of two species form interbreeding and producing viable, fertile offspring.

Block gene flow between the species and limit the production of hybrids.

Question 7

Hybrids

Answer 7

Offspring that result from an interspecific mating.

Question 8

Pre-zygotic Barriers

Answer 8

“Before the zygote” block fertilization from occurring. Such barriers typically act in one of 3 ways.

1) By impeding members of different species from attempting to mate
2) By preventing an attempted mating from being completed successfully
3) By hindering fertilization if mating is completed successfully

Question 9

Post-zygotic Barriers

Answer 9

“After the zygote” a variety of barriers may contribute to reproductive isolation after the hybrid zygote is formed.

Examples:
Developmental errors may reduce survival among hybrid embryos.

Problems after birth may cause hybrids to be infertile or decrease their chance of surviving long enough to reproduce

Question 10

Biological Species Concept

Answer 10

According to this concept, a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring-but do not produce viable, fertile offspring with members of other such groups.

Question 11

Morphological Species Concept

Answer 11

Distinguishes a species by body shape and other structural features. Can be applied to sexual and asexual organisms, and it can be useful even without information on the extent of gene flow. However, it relies on subjective criteria and researchers may disagree on with structural features distinguish a species.

Question 12

Ecological Species Concept

Answer 12

Defines a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.