Mammalogy Exam 2

Discuss with Peers: -Describe characteristics of different hair types -Functions or occurence of the different types of molt - Be familiar with the current theory on the origin of mammary glands

Which of the following is NOT an accurate statement about most phylogenies?

Phylogenies represent the known relationship between species

Which of the following variables reduces the probability that two populations of the same species will diverge and form 2 species?

gene flow

Which of the following is NOT a family that is represented in the transition from Artiodactyla to Cetacea?

Cetacetidae

Based on the skull characteristics, what do you predict that this animal eats?

animal material

Which of the following is likely to have the longest digestive tract relative to its size?

a rabbit (herbivore)

Young animals are often much softer than adults. This loss of fur between weaning and adulthood is referred to as the ______ molt.

post-juvenile

Non-cetacean Cetartiodactyla and Perissodactyla vary in their adaptations to unguligrade locomotion. How do they differ?

The feet of Cetartiodactyla have reduced to 2 digits (digits 3 and 4) and the feet of Perissodactyls have reduced to 1 digit (digit 3)

The naming of organisms and the placement of organisms into a hierarchical scheme

Taxonomy

The field of science concerned with resolving the historical or phylogenetic relationships of organisms.

Systematics

Change in gene frequency (and consequentially characteristics of organisms) over time

Evolution

The three most common mechanisms of evolution are:

• Drift

• Gene flow

• Natural selection

Genetic drift arises through _____ and _______

chance events; sampling error

Gene flow arises when there is ____

exchange of genes between populations

Natural selection arises when___

• Individuals have heritable variation in their genes

• Individuals with certain attributes survive/ reproduce better than others

Increasing representation of more fit genotypes =

Evolution by natural selection

New traits/ genomic variation arise from modifications of genes that code for old traits. These modifications include:

• mutations

• change in gene expression

• gene silencing

• gene duplication

For new traits/ genomic variation to be passed down, the changes must be expressed in the ___

germline

The two outcomes of evolution by natural selection are:

• Adaptation (attunement to the environment)

• Speciation (new species arise)

Change within a lineage over time

Anagenesis

Adaptation relates to Anagenesis because____

Multiple adaptations over time lead to anagenesis in a species

Lineage splitting

Cladogenesis

Speciation relates to Cladogenesis because___

Cladogenesis is a pattern of speciation where one ancestor branches into multiple distinct, independent descendant species

A phylogenetic group comprised of an ancestor and all descendants

Clade

A complete clade that contains all descendants and includes no taxa that are not descendants

Monophyletic group

A hypothesis of the evolutionary relationships of a group of organisms

Phylogeny

An old approach to constructing phylogenies based on the overall similarity of the organisms

Phenetics

A more current approach for constructing phylogenies based on shared derived characters

Cladistics

If a trait is ancestral, it ___

existed in a common ancestor and was passed down to descendant species

If a trait is derived, it ___

evolved in a lineage after it split from a common ancestor; the ancestor did not have it

Types of data used to build phylogenies include:

• Morphology

• Fossils

• Embryological development

• Vestigial structures

• DNA sequence

To build phylogenies with a phenetic approach, different types of data must be used to ___

Quantify similarity

Trees developed using phenetic methods are a __

Phenogram

A problem with phenetics where two species have similar characteristics due to inheriting them from a common ancestor

Homology

A problem with phenetics that confounds quantified relatedness where two species have characteristics similar in form but evolved independently.

Homoplasy

The goal of cladistic approaches is to use____

homologous traits to describe relatedness

The method used when building phylogenies using a cladistic approach is to ___

identify homology using hypotheses about evolutionary patterns

What is the principle of parsimony?

The simplest phylogeny is the correct phylogeny (aka tree with fewest reversals and incidences of convergence)

A collection of species on a clade that includes all living (extant) members of a linage, their most recent common ancestor, and all the descendants (living or extinct) of that common ancestor

Crown group

A group of extinct organisms that are more closely related to a specific living group (crown group) than to any other living group, but are not part of that living group themselves.

Stem group

The process of disrupting gene flow between populations

Speciation

The transfer of genes between populations; works against speciation

Gene Flow

Anagenesis leads to cladogenesis if ____

gene flow between groups is stopped

Complete mixing of genotypes across a population

Panmixia

Unequal distribution of genetic variation across a population

Genetic structure

A gradual change in phenotype across a species’ range

Clinal Variation

Speciation arising from divergence of populations that are physically separated in time and space

Allopatric speciation

Speciation arises within a population that is not separated in time and space

Sympatric Speciation

How long before there is greater than 2% genetic divergence in the species-level differences?

1 million years

How long before there is a fixed genetic difference and the possibility of a slight divergence in appearance?

10,000 years

How long before you can start to get major divergence in ecology, body plan, etc.?

10 million years

How long before there is mammalian diversity in a population?

Approx. 225 million years

How long until there is eukaryotic diversity?

Approx. 2 billion years

If the hybrid of two species does not survive to reproductive age, has low fitness, or is sterile, it is considered a ____

Post- zygotic barrier

What is the most common form of speciation in mammals and other animals?

Allopatry

The species concept where species are reproductive units and defines a species as any interbreeding population reproductively isolated from all other populations.

Biological Species Concept

In the Biological Species Concept, the basis for discriminating species is ____

Hybrid breakdown

The species concept that defines a species as any group of organisms with a unique evolutionary history, as diagnosed by one or more traits

Phylogenetic Species Concept

In the Phylogenetic Species Concept, hybridization is ____

irrelevant

The species concept that defines a species as any group of organisms that is genetically isolated from other such groups or any diagnosable (differentiable) group as a species if there’s <2% divergence

Genetic Species Concept

The Genetic Species Concept requires hybrid breakdown, meaning interbreeding cannot___

contribute to substantial gene flow

The species concept that defines a species as a genetically isolated population from other by incompatibilities in uniquely coadapted mitochondrial and nuclear genes

Mitonuclear Compatibility Species Concept

In the Mitonuclear Compatability Species Concept, _____ _____ is key.

hybrid fitness

The coordination of function by the products of the mitochondrial genome and the nuclear genome to achieve oxidative phosphorylation

Mitonuclear Coadaptation

Mitonuclear coadaptation is maintained by ___

Coevolution

Was the dominant land animal for 70 mya until the rise of the dinosaurs; would diversify again in the Cenozoic; origin was 320 mya and would give rise to mammalian lineage ~200 mya later

Synapsida

Put the following in order from mose ancestral to most recent:

a) First birds

b) First dinosaurs

c) First true mammals

d) The vertebrate lineage that gave rise to mammals

e) Lost non-avian dinosaurs

d, b, c, a, e

Origin of the earth was ___

4.54 billion years ago

First organisms/ bacteria arose around ____

4.1-3.5 billion years ago

First vertebrates arose around ___

525 million years

First tetrapods arose around ___

375 millions years ago

The members that would become the lineage to mammals arose in the ___ period or ____ mya.

Pennsylvanian; 320

The first dinosaurs arose in the ____ period, or ___ mya.

Triassic; 250

The first mammals arose in the ____ period, or ____ mya.

Triassic; 200

The first birds arose in the ___ period, or ____ mya.

Jurassic; 150

Early amniotes gave rise to the 2 major lineages:

• Diapsids

• Synapsids

The first amniotes arose ____ mya, while the first synapsids arose ___ mya

330; 320

Was the dominant land animal for 70 mya until the rise of dinosaurs, and would diversify again in the Cenozoic period, also had the distinguishing trait of a single temporal fenestra

Synapsids

Early Synapsids diverged into 2 major taxa:

• Pelycosauria

• Therapsida

The following traits describe the _____ taxa that Synapsids diverge into:

• Small single temporal fenestra

• Do not have reptilian scales

• Some osteoderms and dermal scutes

• May have had glandular skin

• Canine-like teeth develop in derived taxa

Pelycosauria

Name (abbreviated) characteristics of Pelycosauria:

• Small temporal fenestra

• No scales

• Osteoderms and dermal scutes

• Possible glandular skin

• Canine-like teeth

The following traits describe the _____ taxa that Synapsids diverge into:

• Mammalian gait

• Larger temporal fenestra

• Heterodont teeth

• No growth rings in bone (determinate growth)

• Nasal turbinates

• Hair in some based on coprolites

Therapsida

Name (abbreviated) characteristics of Therapsida:

• Mammalian gait

• Large temporal fenestra

• Heterodont teeth

• Determinate growth

• Nasal turbinated

• Possible hair

There would be a dramatic reduction in Synapsid diversity due to the ________, 252 mya.

End Permian extinction

Abundant animals in the Triassic period, derived from a Therapsid group; had mammal-like characters such as:

• Distinct premolars and molars

• Tricuspid molars

• Double-rooted cheek teeth

• Enlarged dentary bone; reduction in size of post-dentary bones

• Atlas and axis differentiate

• Secondary palate

  • Earliest mammary glands

Cynodontia

Name (abbreviated) characteristics of Cynodontia:

• Enlarged dentary bone

• Reduced post-dentary bones

• Postcanine teeth well developed

• Complete secondary molars

Earliest monotreme fossil dates to ____ mya.

100

A group of organisms descended from a common evolutionary ancestor

Monophyletic group

Groups of organisms derived from more than one common evolutionary ancestor

Polyphyletic group

Fossil that comes from Yunnan Province, China and dates back to ~195 mya; has larger brain than conspecifics and has nearly complete mammalian dentary and ear ossicles

Hadrocodium wui

The Hadrocodium wui fossil has great importance because is serves as a crucial _____

reference point for determining how major mammalian lineages branched off and which ancestral traits appeared first.

Using the change in the number of mutations in regions of the genome that mutate at a relatively constant rate for dating

Molecular dating

If there’s an average of 1 base change per 25 million years, and molecular dating tells you that a fossil varies by 8 base changes compared to the living species, how old is the fossil?

200 million years old

The evolutionary splitting and divergence between different biological orders, and involves deeper, older phylogenetic nodes. Under the long-fuse model, this type of diversification is linked to the diversification of angiosperms in the Cretaceous period

Interordinal Diversification

The evolutionary diversification of families, genera, and species within the order, and involves shallower, more recent phylogenetic crown branching. Under the long fuse model, majority of this form of diversification accelerated after the K-Pg extinction left ecological niches vacant by dinosaurs for early mammals to fill

Intraordinal Diversification

Evolutionary timing model that says all diversification occurred within about 10 million years after the K-Pg boundary; supported by fossils

Explosive model

Evolutionary timing model that says interordinal diversification arose in the Cretaceous, order and most intraordinal diversification happened just after the KP-g boundary; supported by DNA

Long fuse model

Evolutionary timing model that says order and families originated in the Cretaceous prior to the KP-g extinctions

Short fuse model

In the Simmons et al. paper, they observe the bat fossil Onychonycteris displays the characteristics of:

• small cochlea in its basicranial region

• keeled sternum

• robust clavicle

• no unambiguous evidence of the ability to laryngeally echolocate

Based on this, did flight or echolocation evolve first in Chiroptera?

Flight

Intermediate species from 55-45 mya in the evolution of Artiodactyla to Cetacea that had the Artiodactyl traits of hooves on toes and 2 trochleae on the astragalus, and the Cetacean traits of a thick inner ectotympanic wall, thick cortex in long bones, and teeth that have oxygen isotope ratio that suggests it lived in water.

Raoellidae

First cetacean species from 50-41 mya that had the Artiodactyl traits of eyes high on the skull and a present astragalus, and the cetacean traits of tooth wear matching a piscivorous diet, and a narrow mandibular joint

Pakicetidae