Species Concepts and Speciation

Question 1

Speciation

Answer 1

process by which one species splits into two species

Question 2

Microevolution

Answer 2

consists of changes in allele frequency in a population over time aka population genetics

Question 3

Macroevolution

Answer 3

refers to broad patterns of evolutionary change above the species level (i.e., the origin of mammals or flowering plants, correspond to a series of speciation events)

Question 4

How do new species originate from existing species?

Answer 4

Over time, populations of a single species connected by gene flow can diverge genetically, giving rise to a new species.

Question 5

Species

Answer 5

basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity

Question 6

What is the classification of life?

Answer 6

Life
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 7

Biological species concept

Answer 7

emphasizes reproductive isolation; a species is a group of population whose members have the potential to interbreed in nature, produce viable, fertile offspring, and do not produce viable, fertile offspring w/ members of other such groups

Question 8

Reproductive isolation

Answer 8

when biological barriers impede members of two species from interbreeding and producing viable, fertile offspring; limit formation of hybrids and therefore gene flow between forming species; can act before or after fertilization of hybrids

Question 9

The biological species concept relies on the disruption or impediment of which aspect of population genetics?

Mutation

Selection

Gene flow

Genetic drift

Answer 9

Genetic flow

Question 10

Prezygotic barriers

Answer 10

block fertilization from occurring by impeding different species from attempting to mate, preventing the successful completion of mating, or hindering fertilization if mating is successful; Ex: habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation

Question 11

Habitat isolation

Answer 11

two species that occupy different habitats within the same area may encounter each other rarely, if at all; Ex; apple maggot flies are isolated from blueberry maggot flies because they feed and lay eggs on different fruits

Question 12

Temporal isolation

Answer 12

species that breed at different times of the day, in different seasons, or different years cannot mix their gametes; Ex: western spotted skunks mate in summer and eastern spotted skunks mate in winter or sunflower populations from the coast of Texas flower earlier than those found inland

Question 13

Behavioral isolation

Answer 13

courtship rituals and other behaviors unique to a species are effective barriers to mating; Ex: many species, including blue-footed boobies, mate only after a unique courtship display

Question 14

Pollinator isolation

Answer 14

species of plant that attract different types of pollinators have a barrier to reproduction; Ex; the flowering plant species Mimulus lewisii and M. cardinalis are pollinated by bees and hummingbirds respectively

Question 15

Mechanical isolation

Answer 15

mating is attempted, but morphological differences prevent its successful completion; Ex: genital openings of snails in the genus Bradybaena do not align if their shells spiral in opposite directions

Question 16

Gametic isolation

Answer 16

sperm of one species may not be able to fertilize eggs of another species: Ex: surface proteins on the sperm and eggs of different sea urchin species bind poorly to each other, preventing fusion and zygote formation

Question 17

Many tree species are wind pollinated, meaning that they release pollen into the air. If there are many species, which of these reproductive barriers are likely to occur between tree species in the same area?

Behavioral isolation

Gametic isolation

Temporal isolation

Pollinator isolation

Both B and C

Answer 17

Temporal Isolation

Question 18

Postzygotic barriers

Answer 18

prevent hybrid zygotes from developing into viable, fertile adults by reducing hybrid viability, reducing hybrid fertility, or hybrid breakdown

Question 19

Reduced hybrid viability

Answer 19

genes of diff. parent species may interact in ways that impair hybrid’s development or survival in its environment; Ex: the hybrid offspring of diff. subspecies of salamanders of the genus Ensatina do not usually complete development

Question 20

Reduced hybrid fertility

Answer 20

meiosis may fail to produce normal gametes, resulting in sterility, if the parent species have chromosomes of diff. number or structure; Ex: the hybrid offspring of a male donkey and a female horse, a mule, is robust, but sterile

Question 21

Hybrid breakdown

Answer 21

first-generation hybrids are viable and fertile, but offspring in the next generation are feeble or sterile; Ex: hybrids between certain strains of cultivated rice are vigorous and fertile, but members of the next generation are small and sterile

Question 22

What is a limitation of the biological species concept?

Answer 22

Number of species to which it can be applied to is limited; cannot be applied to extinct or asexual organisms because mating cannot be observed

Question 23

Morphological species concept

Answer 23

distinguishes a species by its structural features; applies to sexual and asexual species and does not require information of the extent of gene flow; disadvantage: relies on subjective criteria (could be disagreements)

Question 24

Ecological species concept

Answer 24

defines a species by its ecological niche, the sum of its interactions w/ the nonliving and living parts of the environment; applies to sexual and asexual species and emphasizes the role of disruptive selection

Question 25

Summary of species concepts

Answer 25

Biological species concept
-Emphasizes isolation, differences, and how separate species are

Morphological species concept
-Emphasizes unity of species, how similar they are

Ecological species concept
-Emphasizes ecological aspects, such as the ecological niche the species occupies

Question 26

Bacteria reproduce primarily in an asexual way. Accordingly, which species concepts is difficult to apply to bacterial species?

Answer 26

Biological species concept because it cannot be applied to asexual species