Zoology, Taxonomy, Systematics

zoology Latin

• zo + ology

• zoin = animals

• logia = study

• scientific study of animals

questions for zoologists

• what are evolutionary realtionships btwn certain animals?

• how diverse ae certain groups of animals?

• what are their characteristics?

• where do they live?

• how do they interact w/ + respond to their envs?

Tree of Life

• model for evolution of life

• describes hypothesized relationship btwn both living + extinct orgs

  • which groups of orgs are more related to each other compared to others

    • animals are subset of Tree of Life

eukaryotes

cells w/nuclei + membrane-bound organelles

eukaryotes to animals

• eukaryotes → unicellular → protozoans

• eukaryotes → colonial

• eukaryotes → multicellular → metazoans

  • metazoans = what we consider animals

characteristics of all animals

• multicellular eukaryotes

• heterotrophs

  • obtain nutrition from consuming other living beings

characteristics of most animals

• motile at some stage of their life

• have specialized sensory organs (eyes, nose, ears. skin)

• have complex nervous systems to respond to their env

• reproduce sexually

taxonomy

• science of naming + grouping organisms

• part of systematics

systematics

compares evolutionary relationships btwn animals + their env adaptations

historical taxonomy

• primary method of distinguishing + comparing groups based on observing morphology (physical features)

• assumes members of same species share characteristics

morphology

• external features

• special organs (ex: genitalia shape)

• anatomy (internal structure)

• embryology (development of embryos + fetuses)

dichotomous keys

• developed to differentiate btwn groups of interest (order, family, genus, species, etc)

• usually comprise couplets (2 statements) followed until taxonomic grouping provided

• still common tools in field guides + other manuals to help biologists learn how to id groups of interest

comparable features of taxonomy/systematics

• karyology

• metabolic pathways

• behaviors like courtship patterns

• ecological characters

• biogeography

• DNA sequences + molecular methods

DNA barcoding

• ID’s spcies thru sample of their DNA on a gene present in all animals

• matched to species w/in giant reference database

• DNA samples can come from:

  • hair, feathers, scales

  • scat, urine, blood

  • digested remains

morphological species concept

• since species don’t change, they have specific physical features that can be used to distinguish them

• led scientists to designate type specimens for museums

• small variations from type specimens were accidental imperfections

• large variations imply diff species

weaknesses of morphological species concept

• some species look very similar but have genetic/behavioral differences that suggest they are multiple species

• species do change over time

  • microevolutionary changes can be observed

biological species concept

• “reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature”

  • capable of reproducing + creative viable offspring

  • doesn’t do so w/other populations of diff species

  • similar ecological properties

weaknesses of biological species concept

• doesn’t consider time dimension, so can only compare living populations

• how to deal w/cases of partial reproductive isolation (ring species)?

• emphasizes interbreeding as criterion of reproduction

  • some species reproduce asexually

ring species

hybrid zones btwn members of diff species where individuals are capable of interbreeding

evolutionary concept

• single lineage of ancestor-dependent populations that maintains its identity from other lineages + that has its own evolutionary tendencies + historical fate

  • common descent

  • applies to sexually + asexually reproducing organisms

  • as long as continuity of features distinguishing species continue in one evolving lineage, it’s one species, + change = new species

species concept = messy + evolving

• many more species concepts

• don’t need to agree with a single one

• exceptions challenge each definition

• species = human construct

  • these definitions can be useful for how we view certain orgs but doesn’t inherently change their reality/properties