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Animal Behaviour & Evolution > Speciation > Flashcards

Speciation Flashcards

1
Q

Speciation

A
  • bridge between pop evolution and taxonomic diversity
  • organism diversity is due to cladogenesis
  • usually too fast for fossil record but to slow for study; largely inference based
  • different animals undergo independent divergence, maintaining separate identities/evolutionary tendencies
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2
Q

Species Classification Function

A
  • COYNE & ORR (2004); species let us:
    1. Systematically classify organisms.
    2. Correspond discrete similar organism groups.
    3. Understand natural discrete organism clusters.
    4. Represent evolutionary history products.
    5. Apply study to largest possible organism variety.
  • necessary for understanding within/between pop variation and sibling species
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3
Q

Sibling Species

A
  • advocates of biological species concept accept genetic “leakage” between species
  • ie. carrion/hooded crow often mistaken as same species as produce hybrids
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4
Q

Linnaean Classification

A
  • all species have a name conforming to binomial/trinomial system (ie. genus/species)
  • ie. giraffe (“giraffa camelopardalis”) = animalia/chordata/mammalia/artiodactyla/giraffidae/giraffa/cameloparalis/reticulata, etc.
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5
Q

Biological Species Concept (BSC)

A
  • MAYR (1942); a species is a group of fertile individuals bared from interbreeding with similarly physiological groups (lest risking parental incompatibility/hybrid sterility) due to reproductive isolation
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6
Q

BSC: Issues

A
  • hybrids do occur (ie. ligers/phickens)

- some males (ie. hybrid flycatchers) are even fertile, though females aren’t

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7
Q

Phenotypic Species Concept (PSC)

A
  • a species is a group of organisms sufficiently similar to one another/different from other species
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8
Q

PSC: Issues

A
  • variation between populations occur
  • ie. latitudinal variation occurs in white-tailed deer
  • CLINE = gradual character change in allele frequencies over geographic distance
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9
Q

PSC-I: Bergmann’s Rule

A
  • BERGMANN (1874)
  • “… within broadly distributed taxonomic clades, pops/large species are found in cold regions, while pops/small species are found in warmer regions…”
  • ie. seagull; wingspan decreases further south in Europe it’s found since less body surface is needed to maintain warmth/travel to the South for the winter as they’re already there
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10
Q

New Species Formation

A

ALLOPATRIC
PERIPATRIC
PARAPATRIC
SYMPATRIC

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11
Q

NSF: Allopatric

A
  • geographic; pops of same species isolates into new ones
  • ORIGINAL POP: full
  • INITIAL SPECIATION STEP: halved via barrier
  • REPRODUCTIVE ISOLATION EVOLUTION: develops in isolation
  • NEW SPECIES AFTER EQUILIBRIATION OF RANGES: overlaps
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12
Q

NSF: Peripatric

A
  • closely related species in isolated into nearby unconnected area
  • ORIGINAL POP: full
  • INITIAL SPECIATION STEP: new niche enters externally
  • REPRODUCTIVE ISOLATION EVOLUTION: in isolated niche
  • NEW SPECIES AFTER EQUILIBRIATION OF RANGES: overlaps born
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13
Q

NSF: Parapatric

A
  • adjacent ranges w/narrow contact zone so species form new area
  • ORIGINAL POP: full
  • INITIAL SPECIATION STEP: new niche enters internally
  • REPRODUCTIVE ISOLATION EVOLUTION: in adjacent/internal niche
  • NEW SPECIES AFTER EQUILIBRIATION OF RANGES: divides w/overlap
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14
Q

NSF: Sympatric

A
  • evolution of new species within same habitat due to reproductive isolation
  • ORIGINAL POP: full
  • INITIAL SPECIATION STEP: genetic polymorphism
  • REPRODUCTIVE ISOLATION EVOLUTION: within pop
  • NEW SPECIES AFTER EQUILIBRIATION OF RANGES: divides w/overlap
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15
Q

NSF: Allopatric (Examples)

A
  • IE. birds of paradise; free to evolve and mix w/few preds in Papua New Guinea
  • IE. Galapagos finches; adaptive radiation in response to different food types (ie. nuts/fruit) on various Galapagos islands, requiring different beaks
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16
Q

NSF: Peripatric (Examples)

A
  • similar to allopatric BUT one pop is much smaller
  • IE. polar bears VS brown bears; polar matriline traced for hypothetical relationship between browns; little known about polars due to climate crisis; hybridization occurred in Ice Ages; divided by drastic climate dispersal events; breeding left strong print
17
Q

NSF-PERI: Matriline

A
  • line of descent from female ancestor to descendant; individuals in all intervening generations are mothers
18
Q

NSF: Parapatric (Examples)

A
  • IE. huge salamander variation (aka. ring species); maybe ancestral species was northern but pops expanded south down San Joaquin valleys
19
Q

NSF-PARA: Ring Species

A
  • extreme forms don’t interbreed in region of new species formation overlap
  • prove INTRASPECIFIC differences can be big enough for INTERSPECIFIC differences = natural variation can generate whole new species
  • IE. new yellow-legged gull from herring gull; looks similar w/smaller wingspan/different legs/leaner build
20
Q

Nature Packaging Concept

A
  • nature is always discretely packaged in tight forms

- if full range according to time/space is studies, apparent boundaries become fluid

21
Q

NSF: Sympatric (Examples)

A
  • species overlap

- IE. cichlid diversity; second set of jaws overlaps within multiple fish

22
Q

Separation Maintenance

A
  • LIFE CYCLE affected by PRE/POST-ZYGOTIC BARRIERS
23
Q

SM: Life Cycle Affected By PZ Barriers

A
  • IE. hamsters; fitness of zygote A impacts number of zygotes in next gen according to current gamete contributions in A
  • PRE = between adult A and mate; prevent further zygote production
  • POST = between zygote A and development; prevent birth
24
Q

SM: Pre-Zygotic Barriers

A 
- prevent/reduce likelihood of gamete transfer to members of another species; ie.
PRE-MATING PRE-ZYGOTIC BARRIERS
- LIMITED DISPERSAL
- ISOLATING (ECOLOGICAL) BEHAVIOUR
POST-MATING PRE-ZYGOTIC BARRIERS
- GAMATE ISOLATION
25
Q

SM: Post-Zygotic Barriers

A
  • consist of reduced survival/reproductive rates of hybrid zygotes; ie.
    HYBRRID UNVIABILITY/STERILITY
26
Q

SM: PRE-Z: PRE-M: Limited Dispersal

A
  • IE. grandparents having been born within 80km of each other; choosing mater based on proximity/clusters immediately available
27
Q

SM: PRE-Z: PRE-M: Isolating Behaviour

A
  • IE. blue-footed booby; mate recognition systems consist of displays/responses to signal potential mates
  • female usually doesn’t respond to inappropriate signals
28
Q

SM: PRE-Z: POS-M: Gamete Isolation

A
  • scheme of fertilization combining invertebrate/mammalian attributes
  • caused via whether sperm sticks to proteins on egg surface for penetration; protein divergence causes it
  • failed union of different species’ gametes; important in externally fertilising species (ie. marine invertebrates)
29
Q

SM: PRE-Z: POS-M: Gamete Isolation (Process)

A
  • VACQUIER (1995); process is:
    1. Sperm chemotactically attracted to egg.
    2. Sperm binds to egg envelope.
    3. Acrosome reaction; externalises contents of acrosomal vesicle.
    4. Sperm holes egg envelope; reaches egg cell membrane.
    5. Membranes of 2 cells fuse; restore diploid genome; activate development.
30
Q

SM: POS-Z: Hybrid Unviability

A
  • often have lower survival rates that “full species”

- mortality intrinsic during embryogenesis due to developmental issues

31
Q

SM: POS-Z: Hybrid Sterility

A
  • mature survival but lack of viable gamete production
  • HALDANE’S RULE (1922); “… when in the offspring of 2 different animal races, a sex is absent/rare/sterile, it’s the heterozygous/heterogametic sex…”
32
Q

SM: Breaking the Barriers

A
  • species barriers broken via experimental crossing

- DIGBY (1912); crossed primula flowers; most were sterile but some weren’t; had double chromosomes (polyploidy) in turn

33
Q

Modern Speciation

A
  • occurs daily
  • ie. all peasant colourations are “phasianus colchicus” regardless of variations/migration patterns; all have same roots but speciation is constantly changing them/adding more collorations/characteristics based on new migratory areas
34
Q

MS: Co-Evolution

A
  • IE. pheasants and their belly bugs differentiating together based on changed environments
35
Q

SUMMARY

A
  • species are variously defined; may arise due to pops of founder species isolating GEOGRAPHICALLY (allopatric/peripatric/parapatric) or BHEAVIOURALLY (sympatric)
  • post-isolation; despite re-encountering, new species remain reproductively isolated due to ingrained adaptation of breeding
  • speciation is a constantly ongoing process

Animal Behaviour & Evolution (10 decks)

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