Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Specimens were collected by bulk plankton tows on the Atlantic Meridional Transect Cruise 22 (AMT22), on RRS James Cook from Oct-Nov 2012.

Data files associated with the publication:
Goetze, E., Hüdepohl, P., Chang, C., Iacchei, M., Van Woudenberg, L., Peijnenburg, K. T. C. A. (2016) Ecological dispersal barrier across the equatorial Atlantic in a migratory planktonic copepod. Progress in Oceanography – AMT special issue. doi:10.1016/j.pocean.2016.07.001

The data files included here were used in all population genetic analyses, which only included stations with sample sizes N > 40. Data files include:
(1) a README file describing the other files;
(2) A fasta file with all unique haplotypes (Goetze_et_al_2016_all_haplotypes.fasta);
(3) An infile formatted for use in Arlequin (http://cmpg.unibe.ch/software/arlequin35/); (Goetze_et_al_2016_plxi_mtCOI.arp);
(4) A population report file that describes the mtCOI haplotype composition of each sample (Goetze_et_al_2016_pop_report.html).

Note: In addition to these files, mtCOI sequences representing unique haplotypes from this study are available under GenBank accession numbers KT429028 - KT429159.

Refer to related dataset "AMT22 Population Samples" for information on population samples included in genetic analyses.

Refer to the following publication for complete methodology details:
Goetze, E., Hüdepohl, P., Chang, C., Iacchei, M., Van Woudenberg, L., Peijnenburg, K. T. C. A. (2016) Ecological dispersal barrier across the equatorial Atlantic in a migratory planktonic copepod. Progress in Oceanography – AMT special issue. doi: 10.1016/j.pocean.2016.07.001

In summary (excerpted from above):
Bulk plankton samples were collected on Atlantic Meridional Transect Cruise 22 (AMT22) between 10/13/2012 and 11/19/2012. Oblique tows were conducted with bongo nets (200 um, 333 um), towed between on average 324 m depth and the sea surface. A General Oceanics flowmeter (2030RC) mounted in the mouth of the 200 um net was used to measure seawater filtered during the tow. Plankton from the 200 um mesh net was bulk preserved immediately in 100% ethyl alcohol, the alcohol was changed to fresh within 12–24 h of collection, and samples were stored at -20 C. Plankton from the 333 um mesh net was sorted live at sea, and Pleuromamma xiphias specimens were preserved immediately in RNALater (Ambion), followed by cryopreservation in liquid nitrogen, and long-term storage at -80 C.

Specimens included in the genetic analyses in this study were collected at 18 stations, located between 39 38.82N and 40 4.39S latitude. The majority of genetic analyses focused on stations with sufficient sample size for population-level inference (N > 42), including AMT22-09 through AMT22-29 and AMT22-45 through AMT22-68. Specimens used in genetic analyses were primarily RNALater-preserved, but some specimens were included from ethanol-preserved samples to achieve the minimum target sample size of 45 individuals per station. When a major genetic break across the equatorial region was identified, we included samples from stations AMT22-31 through AMT22-43 to assess the genetic composition of populations across this region. Population-level analyses were not conducted on these latter stations due to small sample sizes and low abundance in this region, but sequences from these animals were included in the haplotype network. DNA was extracted from individual P. xiphias adults using the DNeasy Blood & Tissue kit (Qiagen), following the manufacturer’s protocol, with the exception of longer elution incubation times (Goetze, 2011). The second of two elutions for each individual was used in this study. Polymerase Chain Reaction (PCR) amplification of a 681-bp fragment of mtCOI was conducted with primers and PCR and sequencing protocols as described in (Goetze, 2011). Forward and reverse sequences from each individual were aligned and checked for errors in Geneious (v7.1.8, Biomatters). Consensus sequences for all individuals were aligned using MUSCLE (Edgar, 2004), and unique mtCOI haplotypes were identified using FABox (http://users-birc.au.dk/biopv/php/fabox/). MtCOI sequences representing unique haplotypes are available under GenBank accession numbers KT429028–KT429159. A minimum spanning haplotype network was inferred for all mtCOI sequences using Population Analysis with Reticulate Trees (PopART; http://popart.otago.ac.nz), in order to investigate geographic patterns in the distribution of haplotypes across the Atlantic.

Population subdivision across samples was investigated using several approaches. Refer to publication cited above.

Description from NSF award abstract:
Marine zooplankton show strong ecological responses to climate change, but little is known about their capacity for evolutionary response. Many authors have assumed that the evolutionary potential of zooplankton is limited. However, recent studies provide circumstantial evidence for the idea that selection is a dominant evolutionary force acting on these species, and that genetic isolation can be achieved at regional spatial scales in pelagic habitats. This RAPID project will take advantage of a unique opportunity for basin-scale transect sampling through participation in the Atlantic Meridional Transect (AMT) cruise in 2014. The cruise will traverse more than 90 degrees of latitude in the Atlantic Ocean and include boreal-temperate, subtropical and tropical waters. Zooplankton samples will be collected along the transect, and mitochondrial and microsatellite markers will be used to identify the geographic location of strong genetic breaks within three copepod species. Bayesian and coalescent analytical techniques will test if these regions act as dispersal barriers. The physiological condition of animals collected in distinct ocean habitats will be assessed by measurements of egg production (at sea) as well as body size (condition index), dry weight, and carbon and nitrogen content. The PI will test the prediction that ocean regions that serve as dispersal barriers for marine holoplankton are areas of poor-quality habitat for the target species, and that this is a dominant mechanism driving population genetic structure in oceanic zooplankton.

Note: This project is funded by an NSF RAPID award. This RAPID grant supported the shiptime costs, and all the sampling reported in the AMT24 zooplankton ecology cruise report (PDF).

Online science outreach blog at: https://atlanticplankton.wordpress.com