Species Differences Flashcards
1
Q
What is a species
A
- Individuals of the samespeciescanreproduceto produce offspring of the samespecies
- Two individuals belonging todifferent speciesnormally cannot produce viable offspring or only produce offspring that is sterile
2
Q
What is reproduction and species differences
A
- Reproduction: Biological process by which new organisms are produced from parents to offspring
- Species Differences: Asexual vs sexual reproduction, oviparity, viviparity and oviviparity, and external vs internal fertilisation
3
Q
What is asexual reproduction and types
A
- Offspring originates from a single organisms and inherits the parents’ genes, no fusion / formation of gametes
- Organisms: Main reproduction form for most single-celled organisms, fungi and plants
- Gemmation: Formation of small buds on the surface of the progenitor
- Fragmentation: Fragments removed from progenitor and develop into new organism
- Parthenogenesis: Offspring develops from unfertilised eggs (arthropods, amphibians)
4
Q
What are the advantages and disadvantages of asexual reproduction
A
- A: Very fast, no gamete formation necessary, advantage for small populations, not very complex, less energy, survival in a stable environment
- D: Offspring is clone of parent (little genetic diversity), environment usually not stable long term (adaptation / evolution), often struggle for existence as well as overcrowding
5
Q
What is sexual reproduction
A
- Sexual: Consists of gamete formation, fertilisation and development of the zygote
- Gametes: Haploid chromosome set, spermatozoa (testes) and ova (ovaries
- Sex Hormones: Males (androgens) and females (oestrogen and progesterone)
- Fertilisation: Leads to a diploid zygote (humans 2n), embryo and later foetus
6
Q
What is oviparity
A
- Fertilised eggs lay outside females body and develop there, no subsequent protection or nourishment
- Embryo receives nourishment from yolk
- Examples: Bony fish, many reptiles, some cartilaginous fish, most amphibians, two mammals, and birds
- A: Less energy, developing embryo = nutrients within yolk, more eggs
- D: Lack of parental investment reduces likelihood of survival
7
Q
What is viviparity
A
- Fertilised eggs are retained inside the female, eggs lack hard outer covering / shell, receives nourishment from mothers blood through placenta or uterine milk
- Develops in female, born alive
- Examples: Marsupials and mammals, some cartilaginous fish and few reptiles
- A: Higher parental investment, high survival
- D: Energy-expensive, low number of offspring
8
Q
What is ovoviviparity
A
- Eggs are fertilised then retained inside female’s body
- Embryos do not receive direct nourishment from mother but from egg’s yolk
- Fully developed when they are hatched
- Examples: Bony fish, some sharks / lizards / snakes / vipers, and some invertebrate animals
- A / D: Protection, intermediate amount of energy, intermediate amount of offspring, intermediate survival probability on average
9
Q
What is external fertilisation
A
- Male and female’s gametes unite outside female’s body
- Fish, crustaceans, mollusks, invertebrates, reef building corals
- Eggs shed by female are fertilised by sperm in external environment (close proximity / timing)
- Affected by water temp, length of daylight, moonlight external stimulus, pheromone cues
- No physical contact
- Individual male courts individual female to release eggs, sperm / ova deposited near one another
- Enormous number of gametes released (chance)
- Aqueous environment (spawning), tend to have no parental care (no certainty of paternity)
10
Q
What is sexual selection
A
- Type of natural selection whereone sex has a preference for certain characteristics in individuals
- Females select traits in males, males compete with each other for access to females for mating
11
Q
What are the 3 types of sexual selection
A
- Sexual Dimorphism: Sexual selection leads to differences in size or appearance between males and females, secondary sexual characteristics e.g. pronounced coloration, increased size
- Mating Systems: Instead of (or in addition to) competing directly with each other to have the opportunity to mate with a female, males can also compete for fertilisation of a female’s eggsaftermating has occurred
- Competing After Mating: Indirect male competition, sperm competition, results in one male being more successful than another at fertilising a female’s eggs
12
Q
What is male first advantage
A
- Allow time for the first male’s sperm to fertilise the eggs
- Mate Guarding: Male remains close to female after mating, prevents other males from mating with her until there has been time for his sperm to fertilise the eggs
- Copulatory Plugs: Sticky residue in male’s ejaculate, temporarily blocks entry to the female’s reproductive tract, physically prevents other males to mate with her
13
Q
What is the baculum
A
- Extra-skeletal bone not attached to the rest of the skeleton, kept in the male’s abdomen, when required, abdominal muscles push penis bone out into the penis causing an erection
- Helps males maintain erection long enough to penetrate a female’s reproductive tract and deliver sperm
- Advantage of speed - mating often has to be quick and opportunistic
- Most primate males have a baculum, also cats, dogs, rats
14
Q
What are differences in marsupial reproductive tracts
A
- Female has two (or 3) vaginas - Both open externally through one orifice but lead to different compartments within the uterus
- Males usually have a two-pronged penis, corresponding to the females’ two vaginas
- Typically develop their offspring in an external pouch containing teats
- Males have prostate and bulbourethral gland but not seminal vesicles
15
Q
What is the cloaca
A
- Singular body opening, posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts
- All amphibians, birds, reptiles, have this combined orifice to excrete both urine and faeces
- Birds reproduce using their cloaca, cloacal kiss (cloaca male to cloaca female), in some birds, males have a phallus