2 Sexual Selection

Question 1

Sex in vertebrates is determined by

Answer 1

many strategies implying genetic, environmental influences, or both

Question 2

Biological Sex Definition

Answer 2

Gamete Size (larger = female)

Question 3

Sexual selection

Answer 3

A form of natural selection that occurs when individuals differ in their ability to compete with others for mates or to attract members of the opposite sex

Question 4

Limits on offspring for males (2)

Answer 4

females

1 male fathers most children - imbalance = competition

Question 5

Limits on offspring for females

Answer 5

increase RS by increasing offspring survival

Question 6

Intrasexual selection….

leads to…

Answer 6

competition for mates within a sex

sexual dimorphism and traits that increase fighting ability, endurance, sperm

Question 7

Distribution of females determines

Results of both (2)

Answer 7

type of competition (contest or scramble)

contest = hierarchies, weapons, mate guarding

scramble = no hierarchies, scramble and sperm competition

Question 8

relative testes size is

Answer 8

larger in primates when females have multiple partners

Question 9

sperm competition (2)

Answer 9

decrease inter-ejaculatory intervals

increase sperm plugs

Question 10

Anisogamy:

Answer 10

the form of sexual reproduction that involves the union of 2 gametes, which differ
in size and/or form. The smaller gamete is called the sperm cell, whereas the larger gamete is called the egg cell.

Question 11

Gamete:

Answer 11

a haploid cell that fuses with another haploid cell during conception, gametes are sex
cells (ovum, sperm).

Question 12

Gonad:

Answer 12

reproductive gland that produces the gametes (testicle produces sperm, ovary produces
egg)

Question 13

Genitals:

Answer 13

external sex organs; visible parts of the body that are involved in sexual reproduction
(penis, vulva)

Question 14

Sex chromosomes:

Answer 14

chromosomes that are involved with determining the sex of an individual. In
humans, each cell nucleus contains 23 pairs of chromosomes, a total of 46 chromosomes. The first 22 pairs are called autosomes. The chromosomes of the 23rd pair are called allosomes often consisting of 2 X chromosomes or 1 X chromosome and 1 Y chromosome.

Question 15

allosomes

Answer 15

chromosomes of the 23rd pair

Question 16

Hormone:

Answer 16

chemical messenger, how one part of your body to communicates with another part
of your body.

Question 17

Sex steroids:

Answer 17

a type of hormones that are produced by gonads (although they can be produced
elsewhere too).

Question 18

Androgens:

Answer 18

testosterone, dihydrotestosterone, androstenedione

Question 19

Estrogens:

Answer 19

estradiol

Question 20

Secondary sexual characteristics:

Answer 20

sexually dimorphic phenotypic traits that are not directly related to the reproductive system and that appear as an individual reaches sexual maturity.

Question 21

Intersex:

Answer 21

A category that describes a person whose reproductive, genetic, genital, or hormonal
configuration doesn’t seem to fit the traditional definitions of male or female. The term “hermaphrodite” is considered outdated and offensive. Intersex is frequently confused with transgender but the 2 are completely distinct.

Question 22

Transgender:

Answer 22

an adjective used to describe a

person whose gender identity does not match the biological sex they were assigned at birth.

Question 23

Covariation:

Answer 23

If 2 traits covary, then they vary together and if you know one trait, you can
successfully predict the other trait.

Question 24

the 3 Gs

Answer 24

(genitals, gonads, and gametes)

covary, to a certain extent

Question 25

mate choice + traits (4)

Answer 25

competition to be chosen by the opposite sex as a mate

ornamentation, courtship, services, friendship

Question 26

sexual conflict = traits (3)

Answer 26

competition by each sex for control over mating and reproduction

vaginal tract, estrus synchrony, sexual coercion

Question 27

male reproductive lifespan is….

Answer 27

short = extreme strategies

Question 28

Infanticide purpose + 3 conditions

Answer 28

by killing an infant a male will gain a reproductive advantage provided that:

• he is not related to the infant he kills
• death of unweaned infant shortens subsequent interval b/t births for mother
• killer increases his chance if mating with the mother and siring her next infant

Question 29

Female counterstrategy to infanticide

Answer 29

confuse paternity

Question 30

Sexual Selection occurs in…

Answer 30

both sexes

Question 31

alternative mating tactics

Answer 31

different behavioral strategies/morphologies