Mammal Reproduction Flashcards
Outline the key characteristics of mammal reproduction?
Internal fertilisation, live birth, young felt with milk produced by mammary glands, born helpless and dependant on parental care, must learn ‘life skills’ for survival.
Describe the characteristics of Monotreme reproduction?
Eggs fertilised in Fallopian tube, eggs receive mucoid membrane which allows them to expand, nourished by maternal secretions, mineralised shell is applied and eggs are laid/incubated by female, young are born very immature.
What is the Allantois membrane responsible for?
Extra-embryonic membrane responsible for gas exchange, blood formation and waste removal.
What is the Amnion responsible for?
Fluid exchange,
What is the Chorion responsible for?
Outermost membrane, involved in gas exchange.
Outline the key characteristics of marsupial reproduction?
Females have two vaginas, while a third, medial birth canal forms between them for birth, 3 vaginas connect, young climb into pouch unaided, tongue advanced so newborn can attach to nipple.
Outline the key characteristics of Eutherian reproduction?
Well-developed placenta - temporary organ comprising maternal and foetal tissues.
Foetus attaches to the placenta via an ublilicus.
Longer gestation time than in monotremes and marsupials, but can produce offspring at later developmental age (precocial birth).
What is the difference between monotreme marsupial and Eutherian female reproductive tracts?
Monotreme = one uro-genital-recal opening (cloaca)
Marsupial = Urogenital opening plus separate rectal opening.
Eutherian = Vagina and rectum separate, urinary tract may be fused or separate from genital tract, uteruses may be separated or fused.
What differences exist between the male monotreme reproductive organ and Marsupial/Eutherian?
In male monotremes, the testes lie in the body cavity so there is no external scrotum, sperm stored in caudal epididymis which is closer to surface of body to keep cool.
In Marsupial/Eutherian, bifid (divided) penis, testicles are external.
What are the function of the placenta?
Physically anchors foetus to the uterus, transports nutrients from the maternal circulation, excretes metabolites to the maternal circulation, produces hormones to regulate organs in both, suppresses maternal immune response..
Why do larger mammals have lower fertility?
Brain devlopment and extended periods of care make fertility an issue in primates, herbivores tend to be large and require precocial births for survival.
What adaption ensure birth occurs at optimal times?
Delayed fertilisation (hibernation), delayed implantation, delayed development, hormones/behaviour/day length.
What might cause social reproductive suppression?
Behavioural (interfere with breeding opportunities, infanticide)
Stress-induced
Pheromonal (chemical cues from dominant individuals suppress reproduction in subordinates).
Where might we observe social reproductive suppression?
Wolves, meerkats, marmots and naked mole rats.
What is social reproductive suppression?
Only 1 female and 1-3 males reproduce; the others are functionally sterile workers, with reproductive functions socially suppressed.
If the ‘queen’ dies, one of the workers will replace her.
