Animal Reproductive Strategies and Development

Comprehensive vocabulary flashcards covering reproductive strategies, fertilization methods, egg structure, embryonic development modes, parental care, and survivorship curves.

Reproductive Effort

The energy used to produce the maximum number of surviving offspring while using the least amount of energy.

Courtship

Behavioral signals or rituals to attract a mate for breeding.

Chemical Courtship

Chemical signals (pheromones) to attract a mate.

Auditory Courtship

Sound signals to attract a mate (calls of singing frogs)

Visual Courtship

Visual displays = male birds showing colourful feathers.

Complex Courtship Displays

Elaborate rituals and physical displays that use alot of energy (extended dances of Blue cranes) = females choose healthier mates with better genes.

How it maximises reproduction

1. Find suitable mates

2. Ready to mate at same time

3. Female conserve energy for mating

External Fertilization

Fertilisation taking place outside the female in water (aquatic vertebrates)

Maximise: huge numbers of gametes are shed into the environment due to low certainty and high predation.

Internal Fertilization

Male gametes are transferred directly into the female (terrestrial vertebrates)

Maximise: increases the certainty of fertilisation and requires fewer gametes.

Cloaca

A single opening in the lower abdomen used by birds and reptiles for copulation and the transfer of sperm.

Ovipary

Eggs are laid + develop outside the mother's body & nourished entirely from egg yolk.

Maximise (aquatic): Lots of eggs (high energy ≠ parental care + small yolk) e.g Catshark

Maximise (terrestrial): few eggs = energy saved

Ovovivipary

Eggs are internally fertilised and kept inside the female until hatching & nourished by a large egg yolk

Maximise: fewer eggs = less energy + born fully developed

Intra-uterine Cannibalism

In ragged-tooth sharks = developing embryos eat their yolk supply + consume other fertilized eggs + developing embryos = 2 surviving pups.

Vivipary

Internal fertilisation where eggs develop into embryos/foetuses inside the mother & nourished by a placenta.

Maximise: less eggs = more energy

e.g hammerhead shark

Amniotic Egg

An egg adapted for terrestrial reproduction that contains four extra-embryonic membranes (amnion, allantois, yolk sac, and chorion) forming fluid-filled protective compartments.

Amnion

Encloses the amniotic cavity, protecting the developing embryo against dehydration and mechanical injury.

Amniotic Fluid

The liquid in the amnion that cushions and protects the developing embryo.

Allantois

Reservoir for nitrogenous metabolic waste.

Chorion

Allows gaseous exchange in amniotic eggs and forms part of the placenta in mammals.

Yolk Sac

Primary nutrition for developing embryo.

Albumen

Food and water reserve

Precocial Development

Offspring hatch/born mobile with open eyes, fully developed legs, and feathers or fur = prenatal parental energy (e.g. ostriches, wildebeest).

Maximise: nourish + protect selves

Altricial Development

Offspring are born naked and blind, confined to nests and need postnatal parental care for warmth, food, and protection.

Maximise: more offspring reach reproductive age

Parental Care

Time and energy by parents after fertilization to improve the survival and reproductive success of offspring.

Maternal Care

Lactation, licking newborns, teaching, and physical protection.

Paternal Care

Feeding young and guarding them against predators.

Type I Survivorship Curve

Convex = K-selected species

High parental care = offspring reach adulthood w mortality among old

Type II Survivorship Curve

Linear (birds) = constant mortality rate in all life stages.

Type III Survivorship Curve

Concave = r-selected species

High mortality among the young w improved survival once established.