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An emerging viral pathogen truncates population age structure in a European amphibian and may reduce population viability

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RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
735 days ago
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
736 days ago
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
736 days ago
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
736 days ago
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
736 days ago
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
736 days ago
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
736 days ago
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
RT @ARC_Bytes: New study: Viral infection may alter age structure of British frog populations https://t.co/YuftO4bpXg #amphibian #conservat…
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Supplemental Information

Supplementary Methods - Population Projection Modelling

A comprehensive overview of the rationale and methodologies behind our populations projection matrix modelling analyses.

DOI: 10.7287/peerj.preprints.27056v1/supp-1

The number of frogs sampled per each population

The number of R. temporaria sampled at each individual population.

DOI: 10.7287/peerj.preprints.27056v1/supp-2

Snout to vent length by age

The relationship between snout to vent length (SVL) and age in R. temporaria from ranavirosis-positive and disease-free populations. We found no significant effect of disease history on the SVL of frogs. Our data does however show clear evidence of continued growth throughout life regardless of disease history.

DOI: 10.7287/peerj.preprints.27056v1/supp-3

The age at which R. temporaria reached sexual maturity by sex and population disease history

The proportion of individuals that reached sexual maturity at each possible age within the summed male and female populations of each disease history. Age at sexual maturity was calculated via skeletochronology.

DOI: 10.7287/peerj.preprints.27056v1/supp-4

Projected populations under different combinations of starting population vectors and transition matrices

Projected population dynamics of R. temporaria populations modelled under different scenarios. Starting population vectors were created by weighted random sampling of 150 animals based on the proportions of each age class observed in populations of each disease history in our data. D-f = disease free and R-p = ranavirosis-positive. Our R-p matrix incorporated decreasing annual adult survival and our R-p starting population vector was age structure truncated.

DOI: 10.7287/peerj.preprints.27056v1/supp-5

Survival elasticities of our population matrices

Computed elasticities of each survival element of our population projection matrices. Elasticities of our matrix which incorporated increasing adult mortality and therefore represented a population subjected to ongoing ranavirosis are shown in red, whilst those of our matrix which represented a disease-free population are shown in blue. For reference the elasticities of an extended matrix created using the unadjusted viral rates published by Biek et al. 2002 are shown in white.

DOI: 10.7287/peerj.preprints.27056v1/supp-6

Fecundity elasticities of our population matrices

Computed elasticities of each fecundity element of our population projection matrices. Elasticities of our matrix which incorporated increasing adult mortality and therefore represented a population subjected to ongoing ranavirosis are shown in red, whilst those of our matrix which represented a disease-free population are shown in blue. For reference the elasticities of an extended matrix created using the unadjusted viral rates published by Biek et al. 2002 are shown in white.

DOI: 10.7287/peerj.preprints.27056v1/supp-7

Basal population matrix

Basal population matrix. Row one represents the fecundity of all life stages on the horizontal into the egg life stage, the number is equivalent to females produced per female. All other rows represent the proportional survival of each age class on the horizontal to the relevant age class on the vertical aspect of the matrix.

DOI: 10.7287/peerj.preprints.27056v1/supp-8

Population projections under varying decreases in per annual survival rates of adult R. temporaria

Population dynamics of theoretical disease-free populations and theoretical ranavirosis-positive populations modelled with an increasingly large annual percentage increase in adult mortality due disease. We found no significant difference between the population estimates through time based on varying this survival parameter alone (ANOVA; df = 6, F=0.889, p=0.505). In the absence of an empirically proven value for this parameter, we selected a value of 5% annual increase in mortality to represent the probabilistic increase of succumbing to ranavirosis with an increasing number of years returning to breed within the same infected population.

DOI: 10.7287/peerj.preprints.27056v1/supp-9

Matrix representing spawning failure in a ranavirosis-positive population

Population matrix representing complete spawning failure in ranavirosis-positive populations (5% reduced survival per year for adults). Row one represents the fecundity of all life stages on the horizontal into the egg life stage, the number is equivalent to females produced per female. All other rows represent the proportional survival of each age class on the horizontal to the relevant age class on the vertical aspect of the matrix.

DOI: 10.7287/peerj.preprints.27056v1/supp-10

Matrix representing spawning failure in a disease-free population

Population matrix representing complete spawning failure in disease-free populations. Row one represents the fecundity of all life stages on the horizontal into the egg life stage, the number is equivalent to females produced per female. All other rows represent the proportional survival of each age class on the horizontal to the relevant age class on the vertical aspect of the matrix.

DOI: 10.7287/peerj.preprints.27056v1/supp-11

Matrix representing mass mortality in ranavirosis-positive populations

Population matrix representing a year with a mass mortality event in ranavirosis-positive populations. Row one represents the fecundity of all life stages on the horizontal into the egg life stage, the number is equivalent to females produced per female. All other rows represent the proportional survival of each age class on the horizontal to the relevant age class on the vertical aspect of the matrix.

DOI: 10.7287/peerj.preprints.27056v1/supp-12

Matrix representing a mass mortality and spawning failure in a ranavirosis-positive population

Population matrix representing a year with a mass mortality event and total reproductive failure in ranavirosis-positive populations. Row one represents the fecundity of all life stages on the horizontal into the egg life stage, the number is equivalent to females produced per female. All other rows represent the proportional survival of each age class on the horizontal to the relevant age class on the vertical aspect of the matrix.

DOI: 10.7287/peerj.preprints.27056v1/supp-13

Additional Information

Competing Interests

Xavier A Harrison serves as an Academic Editor for PeerJ.

Author Contributions

Lewis J Campbell conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.

Trenton W J Garner conceived and designed the experiments, contributed reagents/materials/analysis tools, authored or reviewed drafts of the paper, approved the final draft.

Giulia Tessa performed the experiments, contributed reagents/materials/analysis tools, authored or reviewed drafts of the paper, approved the final draft.

Benjamin C Scheele analyzed the data, authored or reviewed drafts of the paper, approved the final draft.

Amber G F Griffiths authored or reviewed drafts of the paper, approved the final draft.

Lena Wilfert authored or reviewed drafts of the paper, approved the final draft.

Xavier A Harrison analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.

Animal Ethics

The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):

This work was approved by the ethics committees of both the University of Exeter and the Institute of Zoology.

Field Study Permissions

The following information was supplied relating to field study approvals (i.e., approving body and any reference numbers):

UK Home Office

Data Deposition

The following information was supplied regarding data availability:

GitHub

https://github.com/zoolew/Ranavirus-FrogDemography

Funding

This work was supported by a Natural Environment Research Council PhD Studentship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.


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