Data from: Evidence for gene flow from the Gulf of Mexico to the Atlantic Ocean in bonnethead sharks (Sphyrna tiburo)
Data files
Nov 13, 2024 version files 712.01 KB
-
bams.qc
814 B
-
Bonnet2_1.qopt
2.14 KB
-
Bonnet2_2.qopt
4.18 KB
-
Bonnet2_3.qopt
6.23 KB
-
Bonnet2_4.qopt
8.28 KB
-
Bonnet2.ibsMat
71.38 KB
-
Bonnethead_2bRAD.sh
15.97 KB
-
Bonnethead_popstructure.R
10.23 KB
-
Bonnets_meta.txt
10.08 KB
-
d2.sfs
34.56 KB
-
README.md
1.85 KB
-
sfs.zip
546.29 KB
Abstract
Gene flow is important for maintaining the genetic diversity required for adaptation to environmental disturbances, though gene flow may be limited by site fidelity in small coastal sharks. Bonnethead sharks (Sphyrna tiburo) - a small coastal hammerhead species - demonstrate site fidelity, as females are philopatric while males migrate to mediate gene flow. Consequently, bonnetheads demonstrate population divergence with distance and Atlantic populations are genetically distinct from those of the Gulf of Mexico. Indeed, Florida forms a vicariant zone between these two bodies of water for many marine species, including some sharks. However, while bonnetheads are expected to have limited dispersal, the extent and rate of bonnethead migration remains uncertain. Thus, we aimed to determine their dispersal capacity by evaluating connectivity between disparate populations from the Gulf of Mexico and Atlantic Ocean. Using 10,733 SNPs derived from 2bRAD sequences, we evaluated genetic connectivity between Tampa Bay on the Gulf Coast of Florida and Biscayne Bay on the Atlantic coast of Florida. While standard analyses of genetic structure revealed slight but significant differentiation between Tampa Bay and Biscayne Bay populations, demographic history inference based on the site frequency spectrum favored a model without divergence. However, we also estimate that if population divergence occurred, it would have been recent (between 1,500 - 4,500 years ago), with continuous unidirectional gene flow from Tampa Bay to Biscayne Bay. Our findings support the hypothesis that bonnetheads can migrate over relatively large distances (>300 miles) to find mates. Together, these results provide optimism that under proper management, a small-bodied globally Endangered shark can undergo long migrations to sustain genetic diversity.
README: Genomic evidence for bonnethead shark (Sphyrna tiburo) migration from the Gulf of Mexico to the Atlantic Ocean
https://doi.org/10.1002/ece3.70334
Description of the data and file structure
Bonnethead_2bRAD.sh
contains instructions to trim and filter reads, genotype samples, run GADMA for demographic inference, and calculate Fst and inbreeding coefficients. Data input for these scripts include: d2.sfs
(site frequency spectrum for GADMA) and "sfs
" (folder): contains 100 bootstrapped sfs for custom model selection procedure. All genetic data can be accessed from the Sequence Read Archive under Bioproject: PRJNA1082259 (Accession nos.: SAMN40202348- SAMN40202454).
Use Bonnethead_popstructure.R
to reproduce figures and results from the manuscript- including dendrograms and PCoA of IBS and relatedness genetic distances, Admixture barplots, and RDA biplots. Data input for these scripts include: bams.qc
(list of bam files or individual samples), Bonnet2.ibsMat
(Identity-by-State genetic distance matrix), four *qopt
files (for admixture scenarios k=1-4), and Bonnetsmeta.txt
(containing site and morphological information for each sample).
Variables in Bonnets_meta.txt
include:
TubeID: Extra tube labels during sample collection
Maturity_fieldob: Four maturity designations (YOY, immature, subadult, mature) estimated during sample collection
Sex: Male/ Female
Location: Site names during sample collection
PCL (cm): Precaudal length
FL (cm): Fork length
TL (cm): Stretched total length
Girth (cm)
Eye2eye (cm)
Bluge_slope (cm)
Mouth_width (cm)
Maturity (cm): Mature, immature only
Code/Software
Reads are deposited in the SRA (Bioproject: PRJNA1082259). We used the Texas Advanced Computing Center (TACC) for all bioinformatic analyses. All figures were produced in R.