DOI: 10.6086/d1zx02
title: Data from: Differential habitat use and recruitment facilitate coexistence in a community with intraguild predation

description: Theory predicts that species engaged in intraguild predation (IGP) can
 only coexist under limited conditions, yet IGP is common in nature.
 Habitat complexity can promote co-existence by reducing encounter rates,
 but little is known about the contribution of differential habitat use. We
 hypothesized that differential use of alternative habitats promotes
 coexistence of an IG predator and prey. We evaluated predictions of this
 hypothesis with an experimental introduction of an IG predator fish into
 four natural stream communities that previously contained only the IG prey
 fish. We monitored the development of this IGP over the course of four
 years to determine how each species used alternative stream habitats. The
 introduced species prefers pool habitats while the resident species was
 more evenly distributed across pools and riffles. The density of the
 resident decreased in the pool habitat preferred by the invader,
 accompanied by a local increase in the mean of the resident size
 distribution. Selective predation by the invader on hatchling residents
 appears to impact the residents’ demographic response. The continued
 recruitment of resident juveniles in riffles, where the introduced species
 is rare, facilitated the persistence of the resident. This differential
 use of habitats was not accompanied by a change in the resident’s growth
 rates in either habitat. Our results show that differential habitat
 selection and recruitment promoted persistence during an invasion
 involving IGP, which helps to bridge the gap between theory and
 observation in explaining coexistence in IGP systems. 
description: <i>Preliminary site preparation: </i>We introduced guppies into four KO headwater streams in the upper Guanapo River watershed. These streams exhibit a pool-riffle structure where permanent pools alternate with rocky riffles. Other habitat types exist, such as seepages and flood pools. We combine these subcategories into a single, non-pool category, hereafter “riffles”. Barrier waterfalls separate fish populations and communities occupying this pool-riffle mosaic into defined sections of stream “reaches”. The Introduction and Control reaches each have long stretches of stream with good pool-riffle development and barrier waterfalls which confined guppies within the Introduction reach. In association with other goals of the transplant experiment, we thinned the tree canopy in the Control and Introduction portions of two streams (UPL and TAY) and in that way increased primary productivity. <i>Transplant and sampling procedures: </i>We transplanted guppies into LOL and UPL in March 2008 and into CAI and TAY in March 2009. LOL and UPL each received 78 guppies and CAI and TAY each received 104 guppies with an even sex ratio in all four streams. Introduction reaches varied from 65 to 150 m in length. Killifish Control reaches were upstream of the guppy Introduction reaches, above barrier falls that prevented further upstream movement of introduced guppies. Control reaches varied from 26 to 62 m in length.  We censused guppy populations every month during daylight hours. We sampled pools and riffles with dipnets with the goal of capturing all guppies &gt; 14 mm standard length. Guppies from each pool or riffle were kept separate, as were males and females. All fish were measured, marked by subcutaneous injection of colored elastomer (Northwest Marine Technologies, Shaw Island, Washington, USA) then released at the point of capture.  We sampled killifish with aquarium dipnets after dark with headlamps because they are more easily seen and caught at night. We also used baited minnow traps in deeper pools. Captured fish were separated by location of capture and transported to the laboratory where each fish was measured (total length), weighed, marked in the same fashion as guppies, then returned to the point of capture. We classified the habitat type, pool or riffle, at the time and place of each individual capture. We standardized sampling procedures, e.g. times and personnel, to minimize variation in effort across habitats and samples, so that the number of captures and resulting size distributions could be compared. We censused the killifish in each stream 6 times per year, beginning 1 year (6 samples) prior to guppy introduction in LOL and UPL and 3 months (3 samples) prior to guppy introduction in CAI and TAY. During the first two years of the study (2007-2008), we captured fish every other month. Beginning in 2009, we altered the sampling schedule to better resolve recruitment and growth of the smaller size classes of killifish. We sampled the streams once each month for three months, then skipped three months and sampled again, once each month for three months. The three-month sampling periods were chosen to represent the dry and wet seasons. Logistical constraints near the end of our study limited sampling in late 2011 and 2012 to a single sample.
description: <strong>mark-recapture dataset</strong>
 site = stream identity reach = reach identity
 (Control or guppy Introduction) fish_id = curated
 individual id code capture_history = a string of 0 and
 1 values. The length of the string indicates the number of sampling
 occasions. Values of 1 indicate an individual was captured on a particular
 sampling occasion and values of 0 indicate no capture on that
 occasion.  <strong>mark-recapture lags
 dataset</strong> site = stream identity<br>
 reach = reach identity (Control or guppy Introduction)<br> date =
 date on which a sample took place<br> lag30 = number of months (30
 days) until the following sample took place
 <strong>habitat-use dataset</strong>
 site = stream identity stream_pair = guppy
 introduction performed in 2008 (coded: 0) or 2009 (coded:1)
 canopy_treatment = intact or thinned canopy
 reach = reach identity (Control or guppy Introduction)
 habitat = pool or riffle habitat species =
 Killifish or Guppy time_since_introduciton = time since
 guppy introduction in months (30 days) stream_length =
 length of stream of each site-reach-habitat locality
 no_captured = number of individuals captured by mark-recapture
 sampling capture_density = no_captured/stream_length in
 individuals per meter log_capture_density = natural
 logarithm of capture_density <strong>recruit
 dataset</strong> site = stream identity
 stream_pair = guppy introduction performed in 2008 (coded: 0) or
 2009 (coded:1) canopy_treatment = intact or thinned
 canopy reach = reach identity (Control or guppy
 Introduction) habitat = pool or riffle
 habitat time_since_introduciton = time since guppy
 introduction in months (30 days) season  = season
 identifier (dry: d; wet: w) search_period = indicator
 for change in killifish sampling protocol pre-2009 (0) and post-2009
 (1) stream_length = length of stream of each
 site-reach-habitat locality adult_n = number of adult
 killifish (&gt;28 mm) captured in sampling event
 recruit_n = number of immature killifish (&lt;28 mm) captured
 in sampling event recruit_density =
 recruit_n/stream_length in individuals/m
 log_recruit_density = natural logarithm of
 recruit_density <strong>growth
 dataset</strong> site = stream identity
 stream_pair = guppy introduction performed in 2008 (coded: 0) or
 2009 (coded:1) canopy_treatment = intact or thinned
 canopy reach = reach identity (Control or guppy
 Introduction) habitat = pool or riffle
 habitat fish_id = curated individual id code
 time_since_introduction_centered = time since guppy introduction
 in months (30 days) centered at the time series mid-point
 total_length_initial = initial total length for the growth
 interval in mm total_length_final = final total length
 for the growth interval in mm time_interval = length of
 growth interval in months (30 days) growth_rate =
 (total_length_final - total_length_initial)/time_interval in
 mm/mo. log_growth_rate = natural logarithm of
 growth_rate <b>size distribution
 dataset</b> site = stream identity
 stream_pair = guppy introduction performed in 2008 (coded: 0) or
 2009 (coded:1) canopy_treatment = intact or thinned
 canopy reach = reach identity (Control or guppy
 Introduction) habitat = pool or riffle
 habitat time_since_introduciton = time since guppy
 introduction in months (30 days) season  = season
 identifier (dry: d; wet: w) no_captured = number of
 individuals captured by mark-recapture sampling
 mean_total_length = mean total length of individuals captured in
 mm