Table S1. List of dytiscid species in lentic sampling localities in southern Alberta. For each species, we have provided its subfamily, number of occurences (Num Loc.), total body length (TL), and whether it was considered a large species for body size analyses (>10 mm TL = TRUE). Species Subfamily Num Loc. TL (mm) >10 mm TL Acilius athabascae Dytiscinae 1 14.18 TRUE Acilius semisulcatus Dytiscinae 24 13.32 TRUE Agabus ajax Colymbetinae 15 9.62 FALSE Agabus ambiguus Colymbetinae 21 8.16 FALSE Agabus antennatus Colymbetinae 49 7.68 FALSE Agabus anthracinus Colymbetinae 50 7.55 FALSE Agabus approximatus Colymbetinae 14 7.87 FALSE Agabus arcticus Colymbetinae 2 7.71 FALSE Agabus audeni Colymbetinae 9 9.56 FALSE Agabus austinii Colymbetinae 18 8.53 FALSE Agabus bicolor Colymbetinae 8 6.87 FALSE Agabus bifarius Colymbetinae 47 6.43 FALSE Agabus canadensis Colymbetinae 62 7.41 FALSE Agabus confinis Colymbetinae 28 8.53 FALSE Agabus congener Colymbetinae 10 7.6 FALSE Agabus discolor Colymbetinae 5 7.25 FALSE Agabus erichsoni Colymbetinae 32 10.23 TRUE Agabus falli Colymbetinae 8 7.17 FALSE Agabus hypomelas Colymbetinae 2 6.79 FALSE Agabus inscriptus Colymbetinae 13 6.59 FALSE Agabus inscriptus inscriptus Colymbetinae 9 6.59 FALSE Agabus kenaiensis Colymbetinae 8 6.11 FALSE Agabus lutosus Colymbetinae 31 8.12 FALSE Agabus margareti Colymbetinae 7 5.7 FALSE Agabus nectris Colymbetinae 20 7.3 FALSE Agabus ontarionus Colymbetinae 6 10.33 TRUE Agabus phaeopterus Colymbetinae 35 6.93 FALSE Agabus pisobius Colymbetinae 4 6.04 FALSE Agabus pseudoconfertus Colymbetinae 4 8.11 FALSE Agabus punctulatus Colymbetinae 64 6.04 FALSE Agabus semipunctatus Colymbetinae 22 6.37 FALSE Agabus smithi Colymbetinae 4 6.59 FALSE Agabus sp. (near approximatus) Colymbetinae 13 7.52 FALSE Agabus strigulosus Colymbetinae 44 6.49 FALSE Agabus tristis Colymbetinae 29 9.84 FALSE Agabus triton Colymbetinae 4 7.15 FALSE Agabus verisimilis Colymbetinae 4 6.39 FALSE Carrhydrus crassipes Colymbetinae 3 12.67 TRUE Colymbetes exaratus Colymbetinae 19 17.57 TRUE Colymbetes longulus Colymbetinae 27 18.02 TRUE Colymbetes seminiger Colymbetinae 17 18.92 TRUE Coptotomus longulus Colymbetinae 27 7.7 FALSE Desmopachria convexa Hydroporinae 2 1.78 FALSE Dytiscus alaskanus Dytiscinae 23 27.4 TRUE Dytiscus circumcinctus Dytiscinae 34 31.2 TRUE Dytiscus cordieri Dytiscinae 23 29 TRUE Dytiscus dauricus Dytiscinae 17 32.9 TRUE Dytiscus fasciventris Dytiscinae 4 26.6 TRUE Dytiscus harrisii Dytiscinae 1 34 TRUE Dytiscus marginicollis Dytiscinae 13 29.7 TRUE Graphoderus liberus Dytiscinae 2 11.54 TRUE Graphoderus occidentalis Dytiscinae 70 12.65 TRUE Graphoderus perplexus Dytiscinae 53 14.65 TRUE Hydaticus modestus Dytiscinae 29 13.2 TRUE Hydrocolus paugus Hydroporinae 12 3.84 FALSE Hydrocolus rufiplanulus Hydroporinae 3 3.1 FALSE Hydrocolus stagnalis Hydroporinae 1 3.36 FALSE Hydroporus appalachius Hydroporinae 15 3.38 FALSE Hydroporus badiellus Hydroporinae 5 2.82 FALSE Hydroporus columbianus Hydroporinae 4 5.75 FALSE Hydroporus criniticoxis Hydroporinae 52 3.27 FALSE Hydroporus dentellus Hydroporinae 12 4.21 FALSE Hydroporus despectus Hydroporinae 35 4.03 FALSE Hydroporus dimidiatus Hydroporinae 1 4.17 FALSE Hydroporus elegans Hydroporinae 11 5.17 FALSE Hydroporus fuscipennis Hydroporinae 29 3.11 FALSE Hydroporus glabriusculus Hydroporinae 15 3.02 FALSE Hydroporus mannerheimi Hydroporinae 15 4.47 FALSE Hydroporus melsheimeri Hydroporinae 3 3.4 FALSE Hydroporus morio Hydroporinae 2 3.31 FALSE Hydroporus notabilis Hydroporinae 39 4.99 FALSE Hydroporus occidentalis Hydroporinae 27 3.18 FALSE Hydroporus pervicinus Hydroporinae 46 4.02 FALSE Hydroporus rectus Hydroporinae 9 4.52 FALSE Hydroporus rufinasus Hydroporinae 17 3.03 FALSE Hydroporus signatus Hydroporinae 5 3.57 FALSE Hydroporus striola Hydroporinae 59 3.18 FALSE Hydroporus tademus Hydroporinae 2 4.56 FALSE Hydroporus tartaricus Hydroporinae 14 3.4 FALSE Hydroporus tenebrosus Hydroporinae 83 4.06 FALSE Hydroporus transpunctatus Hydroporinae 1 4.52 FALSE Hydroporus tristis Hydroporinae 20 3.05 FALSE Hygrotus canadensis Hydroporinae 70 3.68 FALSE Hygrotus compar Hydroporinae 60 3.78 FALSE Hygrotus dentiger Hydroporinae 58 5.32 FALSE Hygrotus farctus Hydroporinae 1 2.18 FALSE Hygrotus impressopunctatus Hydroporinae 102 4.77 FALSE Hygrotus masculinus Hydroporinae 13 4.3 FALSE Hygrotus patruelis Hydroporinae 80 3.82 FALSE Hygrotus picatus Hydroporinae 20 5.06 FALSE Hygrotus punctilineatus Hydroporinae 17 3.93 FALSE Hygrotus salinarius Hydroporinae 13 4.76 FALSE Hygrotus sayi Hydroporinae 56 3.05 FALSE Hygrotus sellatus Hydroporinae 44 3.17 FALSE Hygrotus semivittatus Hydroporinae 11 4.67 FALSE Hygrotus suturalis Hydroporinae 21 3.24 FALSE Hygrotus tumidiventris Hydroporinae 47 4.58 FALSE Hygrotus turbidus Hydroporinae 39 2.9 FALSE Hygrotus unguicularis Hydroporinae 32 5.29 FALSE Ilybiosoma bjorkmanae Colymbetinae 2 9.94 FALSE Ilybiosoma seriatus Colymbetinae 17 8.6 FALSE Ilybius discedens Colymbetinae 20 8.2 FALSE Ilybius fraterculus Colymbetinae 56 10.22 TRUE Ilybius pleuriticus Colymbetinae 4 11.75 TRUE Ilybius quadrimaculatus Colymbetinae 3 10.7 TRUE Ilybius subaeneus Colymbetinae 32 10.46 TRUE Laccophilus biguttatus Laccophilinae 80 4.35 FALSE Laccophilus maculosus Laccophilinae 31 5.75 FALSE Laccornis conoideus Hydroporinae 13 4.85 FALSE Laccornis pacificus Hydroporinae 16 4.7 FALSE Liodessus affinis Hydroporinae 63 2.13 FALSE Liodessus cantralli Hydroporinae 4 1.88 FALSE Neoporus superioris Hydroporinae 18 4.57 FALSE Neoporus undulatus Hydroporinae 7 4.48 FALSE Neoscutopterus angustus Colymbetinae 1 14.82 TRUE Neoscutopterus hornii Colymbetinae 8 15.46 TRUE Oreodytes alaskanus Hydroporinae 3 5.15 FALSE Oreodytes congruus Hydroporinae 1 2.71 FALSE Oreodytes laevis Hydroporinae 3 4.45 FALSE Oreodytes rivalis Hydroporinae 2 2.95 FALSE Oreodytes scitulus Hydroporinae 4 3.62 FALSE Oreodytes snoqualmie Hydroporinae 6 3.6 FALSE Rhantus binotatus Colymbetinae 26 10.36 TRUE Rhantus consimilis Colymbetinae 71 9.48 FALSE Rhantus sinuatus Colymbetinae 2 9.63 FALSE Rhantus suturellus Colymbetinae 21 9.87 FALSE Rhantus wallisi Colymbetinae 46 9.85 FALSE Sanfilippodytes compertus Hydroporinae 16 3.28 FALSE Sanfilippodytes planiusculus Hydroporinae 4 3.06 FALSE Stictotarsus griseostriatus Hydroporinae 50 4.86 FALSE Stictotarsus spenceri Hydroporinae 8 5.69 FALSE Stictotarsus striatellus Hydroporinae 16 4.06 FALSE