Lecture 1 Flashcards
_____ Extant orders
27
_____ Families
167
_______ Genera
1300+
_______ Species
6500+
Where do “new” species come from?
Descriptions form newly explored areas (Expeditions!)
Taxonomic revisions
Species “found” in museum cabinets (mislabelled and someone realized they were misplaced)
Cryptic species
Species that look the same but are genetically distinct
Subtle differences are revealed by:
- Genomics/molecular data
- MRI, CT imaging, 3D laser scanning
- Stable isotope analysis
Cryptic species example
African elephant:
- Savannah elephant
- Forest elephant
Is 6500 species a lot?
NO
- Amphibians have 7000 species
- Reptiles 10000
- Birds >10000
- Fish 32000
- Plants >350000
- > 1000000 insects
Cenozoic Era
“Age of Mammals”
Mammals are the most geographically widespread and morphologically diverse group of vertebrates
66AD-Present
Mammals are:
a) Terrestrial
b) Aerial
c) Subterranean
d) Semi-Aquatic
e) Mostly aquatic
f) Entirely aquatic
g) All of the above
g) All of the above
Mammals have the ______ range of body sizes
Largest
Smallest: Kitti’s hog-nosed bat weighs 1.5g
Estruscan shrew <2g
Largest: Blue whales >180 tons
Why study mammals?
Physiology/Medicine: Used for research purposes, many model mammals
Agricultural pests: Must know how to deter many rats, etc.
Game management: Fish and Game
Zoonoses: Spread zoonotic diseases such as SARS-Cov-2 (Had its origin in 2 kinds of mammals: horseshoe bats and pangolins)
Mammal diversity highlights the processes of evolution: Natural selection, sexual selection, etc.
Apex predators: Many mammals are at the top of the food chain; some are keystone species (have an outsized effect on their particular ecosystem)
Sentinels of ecosystem health (e.g., climate change)
Mammal classification: Why do we classify organisms?
Biologists group organisms to represent similarities and proposed relationships
Classification systems change with expanding knowledge about new and well-known organisms
Mammal Classification: Binomial nomenclature
Two-part name (Genus + specific epithet)
Discovered by Carolus von Linnaeus
Two-word naming system:
- Genus
- -Noun, capitalized
- -Underlined or Italicized
- Specific epithet
- -Descriptive, lower-case
- -Underlined or italicized
i.e. Cervus elaphus (elk in America or red deer in UK)
Mammal classification: Hierarchical classification
Taxonomic categories
Kingdom
Phylum
Class
Order
Family
Genus
SpeciesMammal classification: Systematics
Study of the evolution of biological diversity
Binomen vs. Trinomen
Cervus elaphus (elk or red deer)
Cervus elaphus elaphus
Cervus elaphus canadensis
True powered flight
Evolved 3 times in history: Extinct pterosaurs, birds, and bats (family chiroptera)
Revisions
Linnaeus labelled reindeer as Cervus tarandus (same genus as elk)
Smith revised to Rangifer tarandus
If you see an L, Linnaeus did it
Parentheses indicate a revision
Taxonomies are
Dynamic
Shared generic name indicates a ________-
Close affinity
Cats used to all be in the same genus (Felis spp.) but were separated into
Different groups (Panthera, Puma, etc.)
Felis silvesteris is
wild/domestic cats
Phylogeny reconstruction
Phylogenetic systematics (or cladistics) - developing hypotheses to reconstruct the evolutionary history or relatedness among species
Data for creating a phylogenetic hypothesis come from:
- Molecular characters
- Morphology
- Paleontology
- Biogeography
- Ecological traits
- Behavioral traits
Cladistics Terms: Monophyletic group
group of closely related individuals and their common ancestor
Cladistics terms: Synapomorphy
Trait shared by 2 or more taxa and their common ancestor
Cladistics terms: Symplesiomorphy
AKA ancestral trait; common trait also present in earlier ancestors
A trait shared by 2 or more taxa, but which is also shared with other taxa that have an earlier last common ancestor (e.g. an ancestral trait)
Cladistics terms: Ingroup
The group under study
Cladistics terms: Outgroup
A group or lineage closely related to the group under study
True or False: Mammals evolved after dinosaurs
FALSE
Mammals originated in the Jurassic (were around with dinosaurs); very small at first, underwent a significant adaptive radiation until the Cretaceous (after the mass extinction of dinosaurs; able to become large and fill niches)
Mammals are
Animals Chordates Vertebrates Tetrapods Amniotes Synapsids
Mammals evolved from
Synapsids
Synapsids appeared
~320Mya
The earliest synapsids radiated into:
Diverse herbivorous and carnivorous forms such as the pelycosaurs
Synapsid skull
Lateral temporal opening (absent in diapsids)
