Chapter 2 Sex and Evolution Flashcards
Evolution
The change in the genetic makeup of living populations over time.
Heritable
Capable of being passed down from parent to offspring
Gene
a stretch of DNA that is ttranscribed as a functional unit; a unit of inheritance.
DNA
(Deoxyribonucleic Acid)
the linear molecule that forms the chemical basis of genes in all species except some viruses.
Chromosome
a rod-shaped nuclear organelle composed of DNA and associated proteins
Genome
An organism’s entire complement of DNA, including all its genes.
Conjugation
Contact between two bacteria accompanied by the transfer of a short stretch of DNA (plasmid) from one another.
(1) Gamate
(2) Haploid
(3) Diploid
(1) a specialized call that fuses w another to form a new organism (sperm or ovum)
(2) Possessing healf the usual complement of chromosomes
(3) Possessing the full complement of chromosomes. All cells but gamates
Meiosis
A pair of cell divisions that produces gametes; involves exchange of genetic material between homologous chromosomes & reduction of chromosome # from diploid to haploid.
Explanations for Sexual Reproduction
The main idea is that it limits harmful mutations.
When organisms reproduce sexually harmful mutations can be eliminated. That’s because the offspring receives a randomly selected half of their mother’s genes and half of their father’s genes.
Also, sexual reproduciton might generate beneficial gene combinations.
Red Queen Hypothesis
The idea that sexual reproduction is advantageous because it helps defend organisms againts parasites
Why 2 sexes?
Hermaphrodite
Investment: the commitment or expenditure of resoruces for a goal, such as reproductive success.
An organism that combines male and female reproductive functions.
SRY
(Sex-determining Region of the Y chromosome)
a gene located on the Y chromosome that causes embryo to develop as a male.
Also, there is a connection between sexes and temperature. In some animals low temperatures will develop males and high will develop females. This is not constant among all species.
gestation
Bearing a young in the uterus; pregnancy
Reproductive Strategies: Risk
Males
Max # of potential offspring high
May not be able to find willing mate
Risk: inability to create offspring
Seek to mate WIDELY
Females
Max # of potential offspring low
Plenty of males willing to mate w/ her
Risk: failure of offspring to survive
Therefore, seek to mate WISELY
Pheromone
A volatile compound that is released by one organism and that triggers a specific behavior in another member of the same species.
Females tend to pay attention to
Bodily symmetry.
Fluctuating Asymmetry; a difference between the left and right sides of the body that results from random perturbations of development.
Proceptive Behavior
Behavior of females that may elicit sexual advances by males (courtship behaviors).
Estrus
The restricted period within the ovarian cycle when females of some species are sexually receptive; “heat”
What would happen if the sexes invest the same?
if males and females invest the same, sexual selection may not lead to any marked anatomical or behavioral differences between the sexes.
Remember the seagulls example
Monogamy
Polygamy
Polygyny
Polyandry
Monogamy—2 animals form a Pair Bond
Polygamy—one animal forms a relationship w/ many members of the opposite sex:
Polygyny—many wives
Polyandry—many husbands
Mate Guarding
mate remains close to female during the time in which she is fertile to keep other males away from her
Paternity (DNA) testing.
Sperim competition: By sheer force of numbers, sperm compete with the sperm of other males in the females’ reproductive tracts.
