1: Relict Leopard Frog Part 1 - Taxonomic Confusion

What do species originate from?

along lines of descent from ancestral species

What are species usually composed of?

groups of populations each having spatial and temporal cohesion, maintained by an array of genetic and ecological mechanisms

What is a population?

a group of the same species inhabiting the same area

What was the general region of interest for relict leopard frogs?

Mojave, Sonoran, Arizona, Chihuahan

What is a relict leopard frog?

Rana onca

When were Rana onca discovered?

1875, by Cope from samples collected in Utah

What is a Vegas Valley Leopard Frog?

Rana fisheri

When were Rana fisheri discovered?

1893, by Stejneger from samples collected from a few sites in the Las Vegas Valley

What were Rana fisheri concluded to be in the 1800s?

to just be Rana onca

When were the last specimens of Rana fisheri collected?

1942

After the last specimens of Rana fisheri were collected in 1942, what followed?

extinction

What were likely reasons for the decline/extinction of Rana fisheri?

loss of spring-fed habitat

introduction of exotic predators

What did loss of spring-fed habitats involve?

loss of water, large industrialization

The Las Vegas Valley: Artesian well

Water came from wells in the valley, lakes now continues to lose water

What were some introductions of exotic predators?

bullfrogs, crayfish, fishes, and introduced disease

What are Lowland Leopard Frogs?

Rana yavapaiensis

When were Rana yavapaiensis discovered?

In 1984 by Platz and Frost in Black Canyon

After Rana yavapaiensis was discovered, what was concluded?

That Rana onca was extinct and a new species was found

Rana yavapaiensis included populations found along?

the Virgin River

Systematic/Taxonomic confusion in the 1990s:

Conservation of the remnant populations in Southern Nevada was stymied by the uncertainty

What uncertainty was present about leopard frogs?

Was it:

• One variable species?

• Two distinct species?

• Three distinct species?

Early morphological analysis of regional leopard frogs in 1995 was conducted to address the issue; which included?

PCA on numerous morphometric charcteristics

Frogs on the Virgin River (purported ‘onca’) are physically different than the purported fisheri

Purported onca and yavapaiensis overlap in terms of physical characteristics, but there is a pattern of physical difference

Chiricahua Leopard frog

What are Chiricahua Leopard frogs?

Rana chiricahuensis, main distribution in Arizona

What were fisheri “classified” to be?

academic/extinct

Jennings et al. 1995

• Compared principal Components

• 13 Characteristics in a principal component analysis

What did Jennings et al. 1995 determine?

There were morphological, ecological, and nuclear DNA differences between the species

Historical Distribution of onca

• In the 1990s, frogs only present in three general areas

• By 2001, only a few occupied sites in two general areas

By 2001, only a few occupied sites in two general areas:

two of the remaining sites were extirpated, leading only Northshore and Black Canyon areas occupied

Phylogenetics and phylogeography:

assessing geographic patterns of populations using genetic data

What methods did assessing geographic patterns of populations use?

Phylogenetic tree of MtDNA (Maximum Likelihood Tree)

Multidimensional scaling of RAPD data (nuclear data)

Historical Distribution: Amphibian Survey of Western Grand Canyon

• 46 surveys 2007-2009

• Surprise discovery in Surprise Canyon (Western Grand Canyon)

Phytogeography - onca, yavapaiensis, and Surprise Canyon frogs

MtDNA (N2) haplotype network of MtDNA: 276 samples

Climate Change:

Glacial-interglacial cycles

• Rana onca diverged sometime earlier, surprise canyon animals diverged sometime more recently, but still possess genetic differences

• Climate has fluctuated with warmer and colder periods

  • Lead to expansion, loss of populations, and then lead to differentiations

• Rana onca changed

• Morphologically look very different

Rana onca diverged ___________, while surprise canyon animals diverged ___________

sometime earlier; sometime more recently

Even though Rana onca diverged sometime earlier and Surprise canyon animals diverged sometime more recently, they still:

possess genetic differences

Historical break between yavapaiensis and onca

• Onca and yavapaiensis are distinct species

• Fisheri are extinct (academic), forgettable

What was the hypothesis driving the observed phylogenetic patterns?

With differences in genetic mtDNA, physicality, and nuclear DNA, what was determined about these frogs?

R. onca is distinct from R. yavapaiensis

• Remnant leopard frog populations along Virgin and Colorado rivers are R. onca

Jumping forward to 2001 - Phylogenetic evaluation of fisheri

• Archival DNA

• Tree analysis mtDNA and nuclear genes

• Network analysis of mtDNA

• Alternative explanation for the presence of fisheri

Archival DNA was extracted from?

15 ethanol-preserved leopard frogs collected in 1913 from the Las Vegas Valley

Tree analysis mtDNA and nuclear genes:

Analysis of mtDNA and nuclear DNA

• very genetically different from R. fisheri

What was R. fisheri determined to be genetically?

R. chiricahuensis (Western and South/eastern)

Some form of isolation, sometime in the past, South and eastern R. chiricahuensis was isolated from Western R. chiricahuensis:

evolved for a long time, and came back together

R. fisheri could have ended up in the Las Vegas Valley through some form of human activity, and they retained:

a genetic history of previous isolation

Resolving the systematic/taxonomic confusion:

Determined to be three distinct species, kinda sorta…

Resolving the systematic/taxonomic confusion of R. fisheri:

were extirpated in Nevada, but appears to be the same species as R. chiricahuensis in Arizona

Resolving the systematic/taxonomic confusion of R. onca:

is extant and unique from R. yavapaiensis

Although R. onca is extant and unique from R. yavapaiensis, they were recognized to be?

more similar than some other recognized anuran subspecies (not all that different)

Support from most recent:

unpublished genetic assessment analysis

R. chiricahuensis was endangered and listed, but since they were determined to be the same, R. fisheri has nomenclature priority, thus:

R. fisheri is listed as endangered