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
  • 

  <br /> </p>

  • Hybrid -- intermediate
  • 

  </p>

  • Midwestern/Midland -- single
  • 

  <br /> </p>

• “Ring species”

  • Individuals that ^^don’t interbreed^^ but all stem from ^^one population^^
  • 
  • 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

• 

• 

• 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

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