DOI: 10.5061/dryad.12jm63z91
title: Parasitic mussels induce upstream movement in their fish hosts: early evidence of extended phenotype

description: Parasites often have a large impact on their hosts and can alter host
 phenotype to increase their own fitness, a phenomenon known as extended
 phenotype. Studies demonstrating extended phenotype for non-trophically
 transmitted parasites are scarce. Unionid mussels have a parasitic life
 stage adapted to parasitize fish, which can affect host behaviour, habitat
 use and growth rates, raising the question of whether parasitic freshwater
 mussels can also manipulate their host fish to compensate for downstream
 dispersal and to reach habitats favourable for newly excysted juvenile
 mussels. Wild-caught, parasite-naïve juvenile brown trout (Salmo trutta)
 were PIT-tagged, half infested with parasitic larvae from the freshwater
 pearl mussel (Margaritifera margaritifera), and then returned to their
 home stream. During the following year, trout were tracked to investigate
 movement and habitat use, and also periodically recaptured to measure
 growth and condition factor. The infested trout showed significantly
 higher upstream movement than non-infested trout and were more often
 recaptured in stream sections with slow-moving shallow water, particularly
 during the parasite excystment period (270 days post-infestation). These
 data suggest that the juvenile mussels were successfully transported an
 average of 170 m upstream from the host trout release points to stream
 sections favourable for adult mussels. Infested trout survived as well as
 the non-infested, but had a significantly lower specific growth rate than
 non-infested trout. These results indicate a first example of extended
 phenotype in unionid mussels and highlight the importance of understanding
 glochidia-induced changes to host fish behavioural ecology.
description: # Parasitic mussels induce upstream movement in their fish hosts: early
 evidence of extended phenotype Dataset DOI:
 [10.5061/dryad.12jm63z91](10.5061/dryad.12jm63z91) ## Description of the
 data and file structure Wild-caught trout were microchipped, half of the
 individuals were infested with glochidia, then all fish were released back
 to their home stream. Trout were regularly tracked in the river to measure
 distance moved and habitat use. Trout were also occasionally recaught to
 measure growth.  ### Files and variables Empty cells in dataframes are
 labeled as "null" #### File: Categorizing_habitat.sav
 **Description:**  Provides data on stream mapping Variables included:  SID
 = Section ID FR = Flow Regime (1= Very slow; 2= Slow; 3= Rapid; 4=
 Torrential PS = Primary Substrate (1= mud; 2= sand; 3= pebbels; 4=
 cobbles; 5= rocks; 6= organic matter) Width = section width (m) SS =
 secondary substrate (1= mud; 2= sand; 3= pebbels; 4= cobbles; 5= rocks; 6=
 organic matter height = distance from lake (in 10 m increments) AD =
 average depth (cm) MD = max depth (cm) #### File: DM_(for_resubmisson).sav
 **Description:** Provides data on the distance moved by trout within the
 river. Variables included: isp= inspection event id= Fish ID gloch=
 glochidia presence  Lcat= length category (1= young of the year; 2= one
 summer old; 3= greater than one summer old) Lstr = length (cm) DMs =
 distance moved in sections (10 m increments), calculated from initial
 placement in the river aDMs = absolute value of DMs intDMs = distance
 moved in sections (10 m increments), calculated from previous position
 aintDMs = absolute value of intDMs DMm = distance moved in meters,
 calculated from initial placement in the river aDMm = absolute value of
 DMm intDMm = distance moved in meters, calculated from previous position
 aintDMm = absolute value of intDMm #### File: Growth.sav
 **Description:** Provides data on trout biometrics Variables included:
 FID= Fish ID inf= glochidia presence DPI = days post-infestation W0 =
 starting weight (g) L0 = starting length (cm) W = weight (g) L = length
 (cm) CF = condition factor (ratio of length to weight) SGR = Specific
 growth rate (change in weight over time) #### File: Habitat_Pref.sav
 **Description:** provides data on trout habitat selection (based on PCA
 from Categorizing_habitat) Variables included:  FID = Fish ID gloch =
 glochidia presence W = weight (g) size = length category (1= young of the
 year; 2= one summer old; 3= greater than one summer old) insp= inspection
 event SID = Section ID sec = distance from lake (in 10 m increments) AD =
 average depth (cm) Width = section width (m) RC1 = Rotated component score
 1 (combination of primary substrate and flow regime) RC2 = Rotated
 component score 2 (depth) RC3 = Rotated component score 3 (width) values
 for RC1-3 derived from PCA from the values in the "categorizing
 habitat file" #### File: Survival2.sav **Description:** provides data
 on trout recapture rates (proxy for survival) Variables included:  ID=
 fish ID inf= glochidia presence S2108 = detection (yes/no) of individual
 on 2021-08 sampling event S2109 = detection (yes/no) of individual on
 2021-09 sampling event S2110 = detection (yes/no) of individual on 2021-10
 sampling event S2111 = detection (yes/no) of individual on 2021-11
 sampling event S2201 = detection (yes/no) of individual on 2022-01
 sampling event S2205 = detection (yes/no) of individual on 2022-05
 sampling event S2207 = detection (yes/no) of individual on 2022-07
 sampling event S2208 = detection (yes/no) of individual on 2022-08
 sampling event ## Code/software This data was analyzed with SPSS ## Access
 information NA