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Ecosystem • • • • • • • • Ecosystem Level: Ecological Area = number of species (species richness) Taxonomic definition: Morphology & Life History differences Molecular genetics Phylogenetics tree construction Maintain max. diversity of evolutionary lineages Combining morphological and molecular tools can reveal historical forces = possibly leading to conservation actions or evolutionary explanation of events. Example: Microbial communities Ecotones (between forest and savanna) generation of diversity 1 Defining species 2 Taxonomical Point of View • Groups within a species defined as being of a taxon lower than a species • Zoology = subspecies • Botany = variety, subvariety,form • Conservation Biology = Evolutionary significant units (ESU) [species or smaller distinct population segments] 3 Difficulty in defining "species" and identifying particular species • Species = ?? • Before Evolution Concept: Carl Linneaus invented classification system (religious concept, all creatures already exist) • Hybrid = ?? 4 “Text book” definition • Species = individual organisms from a natural population; generally interbreed and produces fertile offspring (Ernst Mayr) • Exclude unusual or artificial mating: eg. horse to donkey = a mule (sterile) and only occur in captivity 5 Species • Previous definition relies on sexual reproduction • Asexually reproducing organism eg. fungi or certain clone plants the previous definition would not apply • Often difficult to tell based on morphology alone • Natural or experimental hybridization 6 Different way of thinking…. • Barriers to create species – Reproductive (Mating behaviour eg. aerial dance, song, physical trait selection) – Geographical (Pangaea to current geography) Allopatric speciation —Look for historical evidence for possible evolution events 7 Different way of thinking….. • Be careful when sampling; possible Ring species eg. D. Irwin’s study on Greenish warbler • Morphological differences pending source of samples • Possibly no obvious species boundary except at the “end” …otherwise interbreed East Siberia two West Siberia 8 one bar on wing bars Species side by side • Species can diverge while living side by side Sympatric speciation • Cichlid (Amphilophus citrinellus) versus (A. zaliosus) • A. citinellus = prey on snails • A. zaliosus = prey on insect larvae • Evolve different body shape and mating preferences 9 Some examples of species definition Species Definition Textbook (Biological) Individual organism; generally interbreed; produce fertile offspring (E. Mayr) Typological Classical; Fixed properties; Phenotypic based (Linnaeus) Genetic (Phenetic) Similar DNA; DNA-DNA hybridization; Bar coding project (Current) Evolutionary (Darwinian) Shares an ancestor; subspecies Phylogenetics Shares an ancestor; not subspecies (Current) Ecological Adapted to a particular niche 10 Thoughts on species concept • No species concept are entirely objective • Complexity of life the likelihood of objective definition would be impossible • Many disagreements in labeling a species or defining a species • Biologist would settle for what works for them; mixture from different definitions would be ideal 11 Example of species identification • Example of defining different subspecies of Koala bears • Due to dramatic local declines perhaps there are different Koala species • Based on morphology there could be 3 subspecies • Minisatellites, mtDNA, RAPDs and SSRs failed to identify differences • Data show strong North/South continuous cline • Morphological differences possibly due to environment and not genetics (Sherwin et al 2000 Cons Biol 14:639-649) 12 Example of species identification • Sea bird (Petrel) • mtDNA revealed different haplotypes for different morphological types • 3 (B,C,D) for the dark species • 5 (A,E,F,G,H) for the light species • Assortative mating to maintain species differences (Brooke and Rowe, 1996 Ibis 138:420-432) (See Textbook p.78) 13 Example of subspecies • Ursus americanus kermodei (Kermode Bear) • White phase of the black bear (mtDNA confirm) (Marshall and Ritland 2002 Molecular Ecology 11: 685-697) • Possibly due to population isolation, assortative mating (SSR data) • Due to a single nucleotide change (Ritland et al (2001) Tyr-to-Cys 14 Hybrids Abies veitchii Abies homolepis • Interbreeding of two separate species • Using maternal and paternal markers to determine hybrid zones and extensiveness of the zone • Conifer species in Abies (paternal cpDNA and maternal mtDNA) • Using mtDNA, cpDNA and RAPD show hybrid saplings however little adult hybrids 15 Hybrids • Detection of invasive species is very important and an important sign is the detection of hybrids between invasive and native species • Use of molecular markers are especially important for species that lack many morphological differences 16 Individuals • Identification of individuals to species can be difficult pending on life stage (eg. non flowering plants or tadpoles) or lack of morphological characters • To delimit a population, it is important to be able to identify individuals • Biomonitoring by using larvaes is difficult without some kind of unique identifiers • Barcoding of life project will greatly improve these problems but it will not work for many organisms eg. anaerobic organisms, many plant groups, prokaryotes 17 • Forensic investigations calls for identification of suspect and victims • Use of genetic markers great aid in the investigation • Recall VNTR marker usage in previous lecture, can use RAPD, AFLP and now a suite of SNP markers to have compare evidential material with known samples (eg. saliva, hair, tree stumps etc.) 18 Regions for barcoding of life http://www.destination360.com/c entral-america/costa-rica/costarica-animals http://micro.magnet.fsu.edu/optics/olympusmicd/galleries/brightfield /polysiphonia.html http://oceanexplorer.noaa.gov/explorations/04alaska/logs/summary/media/live_bamboo.html 19 Reproduction: determination of Sex • With immaturity and cryptic morphology the identification of the sex of an individual is not always easy • To calculate an effective population size the sex of breeding individuals needs to be identify • Specific primers eg. SRY gene on the Y chromosome can help detect mammalian males • Appropriate control is required to eliminate “false” females by using a housekeeping gene eg. actin • Dart samples from whales to identify individuals and the sex of an individuals is an active area of molecular ecology (Barrett-Lennard, Van. Aquarium) 20 Determination of Sex • Exceptions in standard sexing of mammals such as bird (females = WZ, males = ZZ) there is the helicase DNA binding gene (CHD1) which produce different size products for the WZ chromosomes • Even in plants there is an example of Y (male) specific PCR product eg. hops [diecous plants] 21 Prey vs Predator • Predator-prey interactions, most commonly look at the gut contents to study relationship • Diet analysis eg. prey “crumbles” • Fecal content eg. coyote diet • Tracking predator eg. gut cells in fecal matter • Identify individual prey using mtDNA eg. COI gene, 12S rRNA • Multiple copies of mtDNA great chance of prey amplification 22 Prey vs Predator • Complication of possible secondary prey with PCR techniques, there is a great chance of this problem with non-invasive sampling • Some techniques are more problematic eg. RAPD. AFLP • Usage of specific primers such as SSR will reduce generation of incorrect amplicons, dropout of specific alleles will bias genetic variation estimates • No techniques are 100% error proof • Replication of 10% of samples will be important and negative control when doing PCR must be done 23