NE

FNR24150 -- Week 12 Notes

Introduction

  • each population will %%adapt differently%% and will eventually diverge genetically (%%evolve%%) from other populations
    • if divergence continues, %%speciation%% would occur (%%rare%% outcome)
  • the rate of gene flow is a function of the %%closeness%% of the populations and the %%dispersal%% tendency of the species

Classification

Species

  • Today distinguishes by differences in:
    • @@body function@@
    • @@biochemistry@@
    • @@behaviour@@
    • @@genetic makeup@@
  • ^^Classical Biological Concept Definition:^^
    • ^^genetically distinctive^^ populations of individuals ^^isolated reproductively^^ from all other populations

Alternative species concepts

  • 27-30 concepts
  • Ecological species
    • defined in terms of its ^^ecological niche^^
  • Morphological species
    • defined by ^^morphology^^ (structure)
  • Genealogical species
    • defined as a ^^set of organisms^^ with a ^^common and unique genetic history^^ as shown by ^^molecular patterns^^

Subspecies

  • Def 1:
    • ^^Taxonomic subdivision^^ of a species
  • Def 2:
    • A ^^population^^ of a particular region ^^genetically distinguishable^^ from other populations and capable of ^^interbreeding^^ with them
  • Def 3:
    • A ^^grouping of organisms^^ that differ from other members of their species by ^^color, size, or various morphological features^^

Cline

  • A ^^gradual and continual change^^ in a character by a ^^series of populations^^ or ^^throughout the range of a species^^

  • Usually along a %%geographic or environmental gradient%%

    • Individuals at the two extremes differ

  • Clinal Variation

  • Clinal Variation in plastral markings of painted turtles

    • Western forms -- intricate

    • Hybrid -- intermediate

    • Midwestern/Midland -- single

  • “Ring species”

    • Individuals that ^^don’t interbreed^^ but all stem from ^^one population^^
    • A can breed with Aa, Ab. . . and also A1, A2. . . Aa can breed with anyone on their side, and A1 can breed with anyone on their side; however, A5 & Ae can no longer interbreed with one another
    • Lungless salamander (Ensatina eschscholtzi)

Morphological Variation

  • %%Latitudinal%% changes within a species
    • Changes in body weight; %%Bergman’s rule%%
    • Animals have a tendency to be %%larger%% in %%polar%% regions, %%medium%% in %%temperate%% climates, and %%smallest%% in %%tropical%% ones
    • ==DOES NOT ALWAYS APPLY TO REPTILES & AMPHIBIANS==
    • Changes in body %%color%%

Biogeography

  • %%3 major factors%% influence geographic distributions of amphibians & reptiles

    1. @@Climate@@

      1. Amphibians have 3 factors in regards to climate

      2. @@Temperature@@

      3. @@Rainfall@@

      4. @@Periodicity@@

    2. @@Availability & access to resources@@

    3. @@Dispersal abilities@@

      1. %%Small fossorial%% amphibians & %%reptiles%% have %%poorer%% dispersal abilities
      2. %%Large aquatic%% animals tend to be %%better%% dispersers

Movements

Daily Movements

  • @@Feeding@@
  • @@Thermoregulation@@
  • @@Predator avoidance@@

Seasonal Movements

  • Generally %%more extensive%% but still generally considered to be %%<0.5 km%%
  • @@Breeding@@
    • %%Amphibians%% generally go towards %%water%%
    • %%Reptiles%% generally go towards %%land%%
  • @@Hibernation@@
    • Snakes searching for %%hibernacula%% to escape the cold
  • @@Habitat Utilization@@
    • Largely associated with change in %%food availability%% or %%habitat quality%%

Dispersal

  • Movement ^^outward^^ from ^^home area^^; often implies ^^colonization^^
  • Important for maintaining %%gene flow%% in a population
  • Infers some %%genetic exchange%% (if those dispersing individuals successfully reproduce)
  • %%Undirected movement%% to locations %%unknown%% by the dispersing animals
  • Costs & benefits
    • Benefits
    • %%May reduce intra-specific competition%%
    • Likely to come into contact with different individuals unrelated to you %%(minimizes inbreeding)%%
    • Costs
    • %%Resources%% could be lacking
    • Increased %%predation%% risk

Orientation & Navigation

  • @@Piloting@@
    • %%Simplest%% form; ability to recognize %%landmarks%%
    • Possessed by %%all reptiles & amphibians%%
  • @@Compass orientation@@
    • %%Sense of direction%%
    • %%Independent%% of local cues (i.e. basking/perching sites)
  • @@True navigation@@
    • Ability to orient & move toward a location; an %%internal map%%
  • @@Others@@
    • @@Visual orientation (polarized light)@@
    • @@Pineal organ (salamanders)@@
    • @@Parietal eye (dictates photoperiod)@@
    • @@Olfaction@@
    • @@Celestial (stars & celestial bodies)@@

Orientation in baby Loggerhead Turtles (Chelonia mydas)

  • @@Visual cues@@
    • Uses %%stars & moon%% to help hatchlings find ocean
  • @@Wave Orientation@@
    • Takes them out into the %%ocean%%
  • @@Magnetic Orientation@@

Home Range

  • Seasonal Variation in Home Range Size for Male and Female Spiny Lizard (Sceloporus jarrovi)

  • Home range %%varies%% between the %%sexes%%

    • %%larger in males, smaller in females%%
    • %%male%% home range size %%2x%% amount of female and is %%increasing%%

  • Defense (Territoriality)

    • Usually %%very expensive%%, but where a required resource is insufficient for all individuals, %%defense may have evolutionary advantage%%
    • Types

    1. @@Territorial defense@@

      1. %%Relatively rare%%
      2. Mark territory with %%pheromones%%
      3. Accomplished through %%direct combat%%

    2. @@Site defense@@

      1. %%More common%%
      2. Defense of %%point resource%%
      3. Basking sites, food, nesting