Effects of habitat fragmentation on genetic diversity and population structure in the grassland specialist Cyaniris semiargus inferred from a temporal comparison
(2022) BION03 20221Degree Projects in Biology
- Abstract
- Human-mediated landscape alterations has led to habitat loss for many pollinator species, causing declines in both diversity and abundance. In addition to habitat loss, habitat fragmentation can reduce population connectivity and lead to declines in genetic diversity, the variation that enable adaptation to novel conditions. In spite of this, to which extent pollinator species have lost genetic diversity and suffer from increasing isolation remains an empirical question. Studying the factors that cause loss of genetic variation and isolate populations is necessary for developing efficient conservation strategies, incorporating connectivity. Here, I address whether a semi-natural grassland specialist butterfly, Cyaniris semiargus, that has... (More)
- Human-mediated landscape alterations has led to habitat loss for many pollinator species, causing declines in both diversity and abundance. In addition to habitat loss, habitat fragmentation can reduce population connectivity and lead to declines in genetic diversity, the variation that enable adaptation to novel conditions. In spite of this, to which extent pollinator species have lost genetic diversity and suffer from increasing isolation remains an empirical question. Studying the factors that cause loss of genetic variation and isolate populations is necessary for developing efficient conservation strategies, incorporating connectivity. Here, I address whether a semi-natural grassland specialist butterfly, Cyaniris semiargus, that has lost a large fraction of its historical habitat during agricultural intensification, has experienced reductions in genetic diversity and lost functional connectivity. To this end, I use whole genome resequencing data to compare three pairs of contemporary and historical populations from southern Sweden. I address 1) if genetic diversity is reduced in contemporary populations compared to historical populations from before 1960, 2) if population structure is stronger among modern populations than among historical populations, as expected if habitat loss has increased isolation. How data is filtered strongly affected the outcome of the analyses of genetic diversity, and further adjustments will be necessary before firm conclusions about changes in genetic diversity over time can be drawn. However, clustering analyses show strong population structure in contemporary populations, while the historical populations do not show any population structure. This would be consistent with a decrease in functional connectivity following agricultural intensification. The strong effects of filtering illustrate the importance of careful evaluation of different combinations of filters when comparing the lower coverage lower quality historical DNA to modern. (Less)
- Popular Abstract
- Effects of habitat fragmentation on genetic diversity and population structure in the grassland specialist Cyaniris semiargus inferred from a temporal comparison
Humans have been altering the landscape around them for centuries, especially for agricultural purposes. The agricultural intensification following the WWII together with the extensive use of fertilizers has led to a severe decrease of insect populations, including pollinators. Besides the obvious effects on populations’ decline due to habitat loss, there are underlying threats to the survival of species due to decreased connectivity between remaining populations, as a result of habitat fragmentation. Population mixing is nessecery to maintain high levels of genetic variation... (More) - Effects of habitat fragmentation on genetic diversity and population structure in the grassland specialist Cyaniris semiargus inferred from a temporal comparison
Humans have been altering the landscape around them for centuries, especially for agricultural purposes. The agricultural intensification following the WWII together with the extensive use of fertilizers has led to a severe decrease of insect populations, including pollinators. Besides the obvious effects on populations’ decline due to habitat loss, there are underlying threats to the survival of species due to decreased connectivity between remaining populations, as a result of habitat fragmentation. Population mixing is nessecery to maintain high levels of genetic variation in populations in order for them to be able to adapt to novel environments. When populations become isolated due to habitat fragmentation and intensive land usage, they face increased risk of inbreeding, which lowers the variation in the gene pool, and increases the accumulation of deleterious characteristics. As climate change is pressuring populations to migrate into more fragmented habitats adapt to novel environments faster, it is nessecery to incorporate genomic data into conservation strategies. Given that genetic diversity has dropped by 6% in wild populations in the two centuries, it is necessary to monitor genetic changes in pollinator species to sustain viable populations to prevent ecosystem collapse.
In my study I am comparing the genetic diversity of six populations from southern Sweden, three modern and their historical equivalents from Eastern Scania, Central Scania and Småland. My study species is the mazarine blue butterfly, Cyaniris semiargus whose populations have been declining in southern Sweden as grasslands that contain their larvae host plant have been lost due to agricultural intensification. We collected individuals from contemporary populations during field work in the summer of 2021 and matched them with existing populations from the Entomological collection of the Biological Museum of Lund university. I extracted DNA both from the modern and historical populations and estimated population statistics from their whole genome sequences. Demographic parameters such as nucleotide diversity (pi), population differentiation (FST) and Tajima’s D combined with clustering analyses provide insights into the demographic history of given populations. In my study I compared those estimates for three different filtration levels of the original data since historical DNA can often be damaged, leading to underestimation of population statistics. My results showed increased nucleotide diversity for two out of three filtration levels in contrast to our original prediction of genetic decline. Tajima’s D estimates suggested contraction of the Småland population and expansion of the Eastern and Central Scania populations which consorts with the land usage history of the sampling locations. The clustering analyses show a stronger population structure of the contemporary populations indicating a higher isolation level than in historical populations. Yet, the results of genomic differentiation have been very contrasting with each other between the three levels of filtration I used, making it difficult to draw safe conclusions. My study has showed that the comparison of different filtrations for genomic data is necessary when incorporating ancient DNA in population genomic studies in order to avoid biases caused by underestimation of allelic richness. As the field of bioinformatics is rapidly progressing careful study designs and appropriate pipelines are developed to avoid inconsistences in results when working on ancient and contemporary genomes.
Master’s project degree, 60 credits
Department of Biology, Lund university
Supervisor : Anna Runemark (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9113468
- author
- Jamelska, Patrycja Klara
- supervisor
- organization
- course
- BION03 20221
- year
- 2022
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9113468
- date added to LUP
- 2023-04-14 11:59:26
- date last changed
- 2023-04-14 11:59:26
@misc{9113468,
abstract = {{Human-mediated landscape alterations has led to habitat loss for many pollinator species, causing declines in both diversity and abundance. In addition to habitat loss, habitat fragmentation can reduce population connectivity and lead to declines in genetic diversity, the variation that enable adaptation to novel conditions. In spite of this, to which extent pollinator species have lost genetic diversity and suffer from increasing isolation remains an empirical question. Studying the factors that cause loss of genetic variation and isolate populations is necessary for developing efficient conservation strategies, incorporating connectivity. Here, I address whether a semi-natural grassland specialist butterfly, Cyaniris semiargus, that has lost a large fraction of its historical habitat during agricultural intensification, has experienced reductions in genetic diversity and lost functional connectivity. To this end, I use whole genome resequencing data to compare three pairs of contemporary and historical populations from southern Sweden. I address 1) if genetic diversity is reduced in contemporary populations compared to historical populations from before 1960, 2) if population structure is stronger among modern populations than among historical populations, as expected if habitat loss has increased isolation. How data is filtered strongly affected the outcome of the analyses of genetic diversity, and further adjustments will be necessary before firm conclusions about changes in genetic diversity over time can be drawn. However, clustering analyses show strong population structure in contemporary populations, while the historical populations do not show any population structure. This would be consistent with a decrease in functional connectivity following agricultural intensification. The strong effects of filtering illustrate the importance of careful evaluation of different combinations of filters when comparing the lower coverage lower quality historical DNA to modern.}},
author = {{Jamelska, Patrycja Klara}},
language = {{eng}},
note = {{Student Paper}},
title = {{Effects of habitat fragmentation on genetic diversity and population structure in the grassland specialist Cyaniris semiargus inferred from a temporal comparison}},
year = {{2022}},
}