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
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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
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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)
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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
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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
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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
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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
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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
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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)
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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
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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
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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
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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
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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
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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
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16
Q

What are differences in chicken reproductive tracts

A
  • Yellow orbs are the ova with developing yolk in ovary (bigger ones will be released first)
  • Magnum is larger and adds albumen, isthmus is narrower and adds the membranes
  • Finished eggs exit via vent
17
Q

What are the advantages and disadvantages of sexual reproduction

A
  • A: Introduces genetic diversity, survival in a changing environment, sharing of beneficial genes
  • D: Cost intensive (energy), only 50% of genome contribute to offspring, few offspring
18
Q

What is internal fertilisation

A
  • Male deposits sperm directly into female’s body
  • Sperm deposited in or near female reproductive tract
  • Increased likelihood of fertilisation
  • Protection of embryos and parental care of young
  • Specific individuals are chosen for mating (selection)
  • Fewer gametes but higher survival rate (isolated embryo, limits predation on young)
  • Terrestrial environment, placental mammals, gestation period
19
Q

What is male second advantage

A
  • Elaborate Penis Morphology: Can help to remove sperm of previous males from female’s reproductive
  • Large Quantity of Semen: Large volume of ejaculate helps to flush out the sperm deposited in female’s reproductive tract by previous male, large ejaculate volume, testes also large