Data from: Dispersal-fecundity trade-offs in wild insect populations
Data files
Dec 16, 2024 version files 1.45 GB
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Images-for-repository.zip
1.45 GB
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README.md
3.80 KB
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Stonefly_images_-_key.csv
28.76 KB
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Table_S2.csv
48.45 KB
Abstract
Wing reduction is a common feature of upland insect communities. This phenomenon is thought to be primarily driven by selection against flight, which is typically unfavorable in upland environments due to high winds and cold temperatures. In some insect taxa, wing-reduction has been directly linked to increased fecundity. However, few studies have directly tested for shifts in fecundity linked to flight musculature. Here we test for dispersal-fecundity trade-offs in the widespread subalpine stonefly Zelandoperla fenestrata. Our analysis of 450 stoneflies across 81 localities reveals significant dispersal-fecundity tradeoffs. Specifically, we identify a positive association between the size of their flight muscles and the length of their wings, and a negative association between wing length and ovarian mass. Furthermore, we found a significant negative relationship between flight musculature and ovary mass. These results represent a rare example of a dispersal-fecundity tradeoff in the wild, and illustrate that such tradeoffs can potentially involve corresponding reductions in both flight musculature and wing development. Our findings suggest that widespread taxa subject to variable environmental conditions may benefit from flexible allocation of energetic resources.
README: Data from: Dispersal-fecundity trade-offs in wild insect populations
https://doi.org/10.5061/dryad.mkkwh719d
Description of the data and file structure
We sampled Zelandoperla fenestrata from 2017-2021. Where possible, sampling was conducted from sites where both full-winged and reduced-winged Z. fenestrata ecotypes occur in sympatry. Nymphs were collected by hand from underneath stones or wood in riffle zones, and raised in the laboratory at 11°C in water from their natal stream, until emergence. A total of 450 Z. fenestrata specimens collected across 81 localities (223 females, 227 males) were reared to adulthood in the laboratory, and preserved within 24 hours of emergence.
The forewing and hind tibia lengths of all adult individuals were measured prior to dissection (Images-for-repository.zip), using stereo microscope images calibrated with a micrometer scale in ImageJ (Stonefly_images_-_key.csv). We calculated the relative wing length of all individuals by dividing wing length by hind tibia length. Meso- and meta-thoracic segments (the locations of flight musculature) of both males and female stoneflies were detached from legs, wings, and the remainder of the body. For the majority of female specimens (n = 220), individual ovaries (including maturing eggs) were dissected and stored separately. All isolated segments were then desiccated by heating, and weighed on an analytical balance (Raw_data_-_SF_wing_length.csv).
Files and variables
File: Raw_data_-_SF_wing_length.csv
Description: Morphological measurements from 450 adult Zelandoperla fenestrata stoneflies
Variables:
code = internal reference code
thorax_mg = mass of thorax
body_net_mg = mass of body with thorax removed
body_gross_mg = mass of body
FMR = flight muscle ratio: thorax_mg/body_gross_mg
ovarian_mass_mg = mass of ovaries
ovarian_mass_standardised = (mass of ovaries/(body_gross_mg - mass of ovaries))*10
elevation = metres above sea level
sex = f (female) or m (male)
HTL = hind tibia length
WL = wing length
WL_HTL_ratio = WL/HTL
Blank cells indicate missing data.
Code/software
Microsoft excel can be used to view the data file.
File: Stonefly_images_-_key.csv
Description: Key explaining how to extract morphological measurements from stonefly images (images-for-repository.zip)
Variables:
code = internal reference code
Region = New Zealand region where the sample was collected
Sex = Sex of the individual (M= male, F= female)
WL_scale (pixel/mm): The number of pixels per mm in the image. This information can be used to calculate the wing length (WL) in mm.
WL_pixels: The length of the wing in pixels, as measured by imageJ.
HTL_scale (pixel/mm): The number of pixels per mm in the image. This information can be used to calculate the hind tibia length (HTL) in mm.
HTL_pixels: The length of the hind tibia in pixels, as measured by imageJ.
WL(mm): The wing length of the specimen (WL_pixels / WL_scale).
HTL (mm) = The wing length of the specimen (HTL_pixels / HTL_scale).
WL_HTL_ratio = WL/HTL
Code/software
Microsoft excel can be used to view the data file.
File: Images-for-repository.zip
Description: Raw stonefly images used to extract wing length and hind tibia length measurement (using Stonefly_images_-_key.csv)
Code/software
Images can be extracted into a folder with Winzip (or any software used to unzip files). Wing length and hind tibia length (in pixels) can be measured using ImageJ. The actual wing length (in millimeters) can be calculated by dividing the wing length in pixels by the wing length scales (in pixels/mm). The actual hind tibia length can be assessed in a comparable way.
Methods
We sampled Zelandoperla fenestrata from 2017-2021. Where possible, sampling was conducted from sites where both full-winged and reduced-winged Z. fenestrata ecotypes occur in sympatry. Nymphs were collected by hand from underneath stones or wood in riffle zones, and raised in the laboratory at 11°C in water from their natal stream, until emergence. A total of 450 Z. fenestrata specimens collected across 81 localities (223 females, 227 males) were reared to adulthood in the laboratory, and preserved within 24 hours of emergence.
The forewing and hind tibia lengths of all adult individuals were measured prior to dissection, using stereo microscope images calibrated with a micrometer scale in ImageJ . We calculated the relative wing length of all individuals by dividing wing length by hind tibia length. Meso- and meta-thoracic segments (the locations of flight musculature) of both males and female stoneflies were detached from legs, wings, and the remainder of the body. For the majority of female specimens (n = 220), individual ovaries (including maturing eggs) were dissected and stored separately. All isolated segments were then desiccated by heating, and weighed on an analytical balance.