Reproductive system

Kennedy's notes

Advantages of asexual reproduction

no mate necessary

over time, can create more offspring

perpetuation of successful genotypes

reduction of heterozygosity in populations

advantages of sexual reproduction

increased genetic variation (at least in phenotypes)

works well for motile organisms

works well in stochastic environments

androgens

male sex hormones

asexual reproduction

A reproductive process that doesn't involve fusion of gametes or a change in the number of chromosomes.

Atoke

the anterior sexless part of certain polychaete worms from which grows the sexual portion

baculum

bone that helps penis become erect

Bimodal reproduction

alternating modes of reproduction

changes signalled by environmental and hormonal cues. ex. rotifers

binary fission

A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size. ex. bacteria

birth control

Any method used to reduce births, including celibacy, delayed marriage, contraception; devices or medication that prevent implantation of fertilized zygotes, and induced abortions

Budding

Asexual reproduction in which a part of the parent organism pinches off and forms a new organism. Ex. cnidarians and sponges (porifera)

bulbourethral glands

contribute lubricant fluid to the sperm, and secretions buffer the urethra to neutralize residual acidity

cervix

The opening to the uterus

clitoris

organ of sensitive erectile tissue anterior to the opening of the female urethra

cloaca

common opening for the urinary system, reproductive system, and digestive tract. Found in sharks, amphibians, reptiles, birds, and monotremes

NOT found in mammals, except for monotremes

mammals have separate digestive and reproductive openings

corpus luteum

Endocrine tissue which produces hormones, estrogen, and progesterone which prepares the uterine lining for receiving an embryo

courtship displays

communicate individuals are of the same species and opposite sex, why a female should chose a particular male as a sexual partner

dioecious

a species that has males and females. may not look separate from one another to the naked eye.

disadvantages of sexual reproduction

decreased genetic variation, can be catastrophic in stochastic environments

harder to overcome difficulty

endometrium

lining of the uterus that is highly vascular and continually shed.

Epididymis

A long, coiled duct on the outside of the testis in which sperm mature.

epitoke

a reproductive posterior region, produced as a longitudinal bud, in many Polychaetes

estrous cycle

the female reproductive cycle of mammals other than primates

Eusociality

A complex social structure in which workers sacrifice most or all of their direct reproduction to help rear the queen's offspring. Common in insects such as ants, bees, wasps, and termites.

external fertilization

a mechanism of sexual reproduction. must be done in a moist habitat, and must have synchronous reproduction (reproduce at the same time as other individuals).

Survival rate of offspring is lower, no parental care

Ex. salmon

fallopian tube (oviduct)

female organ that connects the ovary to the uterus; place where fertilization usually takes place. Cilia convey the egg to the uterus.

Female hormonal regulation

cyclic pattern of hormone production

Female reproductive cycle:

Gonadotropin releasing hormone is released by the hypothalamus. It targets the anterior pituitary and causes it to release LH and FSH. Those stimulate the follicle to grow.

Release of GnRH is stimulated by high estradiol and inhibited by progesterone and estradiol.

Surge in LH causes the egg to be released.

Menstrual cycle: follicle develops, released estradiol (positive feedback mechanism). The luteal phase is the second phase. Corpus luteum releases progesterone and estradiol.

Ovarian cycle: endometrium sloughs off when corpus luteum disintegrates. Endometrium thickens over several weeks.

female secondary sex characteristics (estrogens)

Fat in the breasts and hips

Water retention

Affects calcium metabolism

Breast development

Mediates sexual behaviour: not to the same degree as estrous cycles. Libido is affected during cycles.

Follicle-stimulating hormone (FSH)

secreted by the pituitary gland to stimulate maturation of the egg cell (ovum)

follicles

clusters of cells surrounding a single egg (in ovary)

Fragmentation

A means of asexual reproduction whereby a single parent breaks into parts that regenerate into whole new individuals. ex. platyhelminthes and echinodermata (flatworms and starfish)

Gemmule

group of archaeocytes surrounded by a tough layer of spicules; produced by some freshwater sponges

genetic sex determination

chromosomes determine the sex of offspring

Gonadotropin-releasing hormone (GnRH)

Hormone that causes gonadotropin to be released.

Gonadotropins

anterior pituitary tropic hormones, follicles stimulating hormone (FSH) and luteinizing hormone (LH) which stimulate the gonads (ovaries and testes) to produce gametes and to secrete sex steroids

Gonochorism

at any given time, an individual is either male or female.

Haplodiploidism

the total number of chromosomes that determine the sex. The female is diploid and the male is haploid. found in rotifers and some nematodes and insects.

Hemipenes

males have two segments of a penis

found in lizards and snakes

spines keep females from pulling away

Hermaphroditism

A condition in which an individual has both female and male gonads and functions as both a male and female in sexual reproduction by producing both sperm and eggs. maximize output of a copulation event.

Hymenoptera

ants, bees, wasps

internal fertilization

a mechanism of sexual reproduction. Requires cooperative behaviour between males and females, fertilization occurs inside the female individual. Almost always coincides with parental care, which leads to higher offspring success. Ex. humans

intromittent organs

Found in most species that utilize internal fertilization

kin selection

the process by which evolution selects for individuals who cooperate with their relatives. common in eusociality

lagomorphs

rabbits, hares, pikas. Penis is behind scrotum instead of in front.

Leydig cells

produce testosterone

lutenizing hormone

a hormone that stimulates the interstitial cells to begin to secrete testosterone

male (human) reproductive anatomy

testes, epididymis, seminal vesicles, prostate gland, bulbourethral glands, urethrea, penis

male reproductive system

scrotum, penis. meant to deliver sperm to the egg.

marsupial reproduction

have two penes, and reproductive tract of female matches.

menopause

the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines. Estrogen levels lower, decreased responsiveness to gonadotropins

menstrual cycle

Endometrium is shed \= menstruation, causes bleeding and then followed by regrowth of endometrium.

mictic stimulus

stimulus that triggers myxsis (as in rotifers).

can be any type of stimuli.

monoecious

a species that has no males, no females, no sexes. one sex \= no sex.

Monotremes

Egg laying mammals ex. platypus and marsupials

myxis

mixing of gametes (rotifers do this)

nitric oxide (NO)

causes vasodilation in the penis

Ovaries

produce estrogens and follicles (4000), but only a few release eggs. Sit attached to the abdominal cavity

Oviparous

lay eggs

Oviviparous

Type of reproduction in which eggs stay in mother's body after internal fertilization.

ovum/oocyte

a mature egg cell

Parthenogensis (Asexual Reproduction)

using the tools of sexual reproduction for asexual reproduction.

Oocytes develop, but can grow without being fertilized. The egg that is produced is usually already diploid.

previously had an ancestor that used sexual reproduction but went back to asexual reproduction.

Penis

has three layers of spongy erectile tissue

Erectile tissue fills with blood

Pressure seals off the veins

Engorgement causes erection

utilizes the parasympathetic autonomous nervous system, and is therefore involuntary

pheromones

Chemical signals released by an animal that communicate information and affect the behaviour of other animals of the same species.

placental mammals

placenta nourishes young

Primary male sex characteristics

Internal reproductive structures

External reproductive structures

Sperm production

prostate gland

Releases anticoagulant enzymes and citrate

protoandrous

male to female (sequential hermaphroditism)

Protogynous

female to male (sequential hermaphroditism)

Pseudopenis

the phallus of the females of spotted hyenas, caused due to high testosterone levels in females

R-selection

maximizing number of eggs produced. Common in external fertilization