UCM GenBioII Final - Animal Reproduction

asexual reproduction

• one parent

• no reproductive organs or cells

• offspring genetically identical clone of parent

sexual reproduction

• two parents

• gametes produced during meiosis

• zygote formed

• offspring are genetically unique mixture of parents

budding

asexual reproduction

• new individuals arise as an outgrowth from parent

fragmentation

fragments of multicellular organisms can become complete organisms

bisexual reproduction

• union of two genetically different gametes

  • each parent parent produces one kind of germ cell during meiosis (sperm and ova)

monoecious organisms

can self fertilize = sexual reproduction

parthenogenesis

• development of offspring from unfertilized eggs

• typically clones

• can be obligate or cyclical

gynogenesis

• sperm dependents parthenogenesis

• females are spam parasites that mate with heterospecific males

red queen hypothesis

sex should be more common in populations with heavy parasite loads bc genetic variation makes it harder for parasites to adapt to hosts

spermatogenesis

results in the production of four haploid spermatids

oogenesis

meiosis I produces two haploid cells, meiosis II stops at the metaphase and does not continue unless the egg is fertilized

oviparity

egg-laying

• energetically inexpensive

• variable offspring survival

viviparity

live-bearing

• energetically expensive

• allows for behavioral thermoregulation

• high offspring survival

anamniotic

Eggs of aquatic species relying on external fertilization are often jelly-like and can absorb some nutrients from the aqueous environment

amniotic

eggs evolved in terrestrial environments, shelled

amnion

encloses the embryo, cushion

allantois

storage of metabolic waste

chorion

highly vascularized, serves in gas exchange

yolk sac

storage of nutrients

shell

porous, prevents water loss

monotremes

• mammals that lay eggs

• milk patches

metatherians

• marsupials

• short gestation, long parental care

• pouches

eutherians

• placental mammals

• long gestation, short parental care

sex

a distinction based on the type of gametes produced by an individual

gender

a social construct used to describe traits associated with the binary sexes

XX/YY

insects, fish, mammals

• Y-centered = determines maleness

• X-centered = determines femaleness

ZZ/ZW

some insects. fish, mammals

• males are homogametic

• needs two copies of DMRT1 gene for male development

haplodiploidy

hymenopteran insects

environmental conditions can influence development of sex specific traits

ex) location, temp, social

protandry

male → female

protogyny

female → male

primary sexual characteristics

gamete producing and reproductive structures

secondary sexual characteristics

develop later in life, include things such as bright coloration, horns, behavior

more offspring, less energy

smaller

greater fecundity

bigger