Unravelling the complexity of salt marsh ‘Fucus cottonii’ forms (Phaeophyceae, Fucales)

Figures & data

Fig. 1. Co-occurring morphological forms. Individuals of small salt marsh Fucus with narrow thalli adjacent to F. spiralis with broader thalli and receptacles (examples shown by arrows) at Locality 3 (Achill Sound) in June 2014.

Fig. 2. Sample localities in Ireland. Fucus spp. were sampled during 2012 and 2014 at Locality 1 (Illaunnginga), Locality 2 (Clifden) and Locality 3 (Achill Sound).

Table 1. Sampling specifics. Dates of field sampling, taxa sampled and numbers of individuals per taxon examined or processed are presented for: Fucus spiralis (Fs), F. vesiculosus (Fv) and small salt marsh Fucus (ssmF).

Collection information	Locality 1 (Illaunnginga)	Locality 2 (Clifden)	Locality 3 (Achill Sound)
14 & 18 June 2012, taxa sampled:	Fv, ssmF	Fv, Fs, ssmF	Fv, Fs, ssmF
Individuals of ssmF examined under microscope	15	11	17
Individuals of ssmF with receptacles examined	15	11	27
Dried for micro- satellite analyses; taxon (no.)	Fv (10) ssmF (15)	Fv (10) Fs (10) ssmF (15)	Fv (20) Fs (23) ssmF (29)
DNA extraction; taxon (no.)	Fv (10) ssmF (15)	Fv (8) Fs (8) ssmF (8)	Fv (16) Fs (16) ssmF (16)
Individuals success- fully genotyped; taxon (no.)	–	Fv (6) Fs (6) ssmF (5)	Fv (14) Fs (15) ssmF (6)
Voucher samples; taxon (no.)	ssmF (10)	ssmF (12)	Fv (1) Fs (1) ssmF (20)
22–23 June 2014, taxa sampled:	Fv, ssmF	ssmF	Fv, Fs, ssmF
Fixated for nuclear DNA content analyses; taxon (no.)	Fv (9) ssmF (16)	ssmF (10)	Fv (5) Fs (10) ssmF (12)
Nuclear DNA content analyses; taxon (no.)	Fv (3) ssmF (3)	ssmF (3)	Fv (3) Fs (5) ssmF (7)

Figs 3–5. Small salt marsh Fucus with receptacles from: Fig. 3. Locality 1 (Illaunnginga), Fig. 4. Locality 2 (Clifden) and Fig. 5. Locality 3 (Achill Sound). Scale bar is 1 cm.

Table 2. Calculated F_IS, H_exp and allelic richness (Å) for n individuals from populations of Fucus spiralis (Fs), F. vesiculosus (Fv) and small salt marsh Fucus (ssmF) from Locality 2 (Clifden) and Locality 3 (Achill Sound).

Locality-taxon	n	FIS	Hexp	Å
2-Fs	6	0.590*	0.327	1.400
2-ssmF	5	0.271	0.513	2.800
2-Fv	6	0.102	0.570	2.726
3-Fs	15	0.618*	0.295	1.472
3-ssmF	6	0.510*	0.374	2.600
3-Fv	14	0.504*	0.813	4.266

Significant F_IS values are marked with an asterisk. Allelic richness (Å) is standardized to n = 5.

Table 3. Pairwise F_ST values comparing populations of Fucus spiralis (Fs), F. vesiculosus (Fv) and small salt marsh Fucus (ssmF) from Locality 2 (Clifden) and Locality 3 (Achill Sound).

Locality-taxon	2-ssmF	2-Fv	3-Fs	3-ssmF	3-Fv
2-Fs	0.408	0.447	–0.059	0.469	0.238
2-ssmF		0.073	0.492	0.349	0.064
2-Fv			0.526	0.464	0.078
3-Fs				0.497	0.327
3-ssmF					0.182

Table 4. Overview of results from estimated nuclear DNA content from Localities (Loc.) 1 (Illaunnginga), 2 (Clifden) and 3 (Achill sound) of small salt marsh Fucus (ssmF), F. vesiculosus (Fv) and F. spiralis (Fs).

Sample-id	Loc.	Nuclei (n)	2C (SD)	4C (SD)	C (SD)	Receptacles
ssmF-1	2	201	4(0.3)	8.4(0.7)	–	No
ssmF-2	2	184	4.3(0.8)	8.2(0.2)	–	Yes
ssmF-3	2	190	4(0.3)	8.4(0.7)	–	No
ssmF-11	1	172	1.6(0.3)	3.3(0.5)	–	No
ssmF-19	1	208	1(0.1)	3.1(0.2)	–	Yes
ssmF-20	1	164	1.8(0.4)	4.3(0.2)	–	Yes
Fv-27	1	231	1.3(0.3)	2.7(0.3)	–	Yes
Fv-28	1	76	1(0.3)	2.3(0.5)	–	Yes
Fv-30	1	167	1(0.3)	–	0.7(0.2)	Yes
ssmF-36	3	87	1.8(0.5)	–	–	No
ssmF-37	3	153	1.5(0.2)	3.4(0.4)	–	No
ssmF-38	3	69	4.1(0.8)	7.3(0.5)	–	Yes
ssmF-39	3	71	3.9(0.3)	6.4(0.1)	–	Yes
ssmF-40	3	187	4.6(0.6)	7.9(0.6)	–	Yes
ssmF-41	3	173	1.9(0.6)	4.2(0.5)	–	Yes
ssmF-42	3	154	4(0.3)	7.7(0.4)	–	No
Fs-48a	3	247	3.5(0.3)	5.4(0.6)	–	No
Fs-48b	3	151	2(0.4)	3.8(0.4)	0.9(0.2)	Yes
Fs-50	3	104	3.3(0.4)	5.8(0.4)	–	Yes
Fs-51	3	68	3.1(1.0)	5.8(0.8)	–	Yes
Fs-52	3	144	3(0.3)	4.8(0.2)	–	No
Fv-57	3	123	1.8(0.3)	4.4(0.3)	–	Yes
Fv-58	3	83	2.8(0.5)	4.2(0.2)	–	Yes
Fv-60	3	136	1.1(0.3)	2.2(0.3)	0.6(0.1)	Yes

The results are given in pg (± SD) for 2C, 4C and for C (sperm) when possible. Nuclei (n) = number of nuclei examined per sample. Presence or absence of receptacles in the analysed individuals is indicated.

Figs 6–11. Conceptacle structure and germling growth. Fig. 6. Mature oogonium containing egg cells ready to be released; Figs 7-8. Antheridia (Fig. 7) and germlings (Fig. 8) after 6 days in culture from Locality 1 (Illaunnginga) (possible damage to the attachment rhizoids due to transfer to microscope slide). Fig. 9. Immature oogonia from Locality 2 (Clifden). Fig. 10. Immature oogonia. Fig. 11. Antheridia both from Locality 3 (Achill Sound). Scale bar is 50 μm.

Fig. 12. Results from STRUCTURE (A) and INSTRUCT (B) analyses with K = 2; and from INSTRUCT analysis with K = 3 (C). Localities 2 and 3 consist of individuals sampled as Fucus spiralis (Fs), F. vesiculosus (Fv) and small salt marsh Fucus (ssmF). Each individual is represented by a bar and colours represent the proportional assignment to the STRUCTURE/INSTRUCT groups.

Fig. 13. The two first principal components (PC) of a Principal Component Analysis showing genetic affiliation of haplotype composition of ssmF (blue), F. vesiculosus (ves) (green) and F. spiralis (spi) (orange-red) from Locality 2 (Loc2) and Locality 3 (Loc3). The circles represent 95% inertia ellipses for the populations, which characterizes the dispersion of each population around its centre of gravity. Percentages along axes indicate the proportion of overall variability explained by the principal components.

Fig. 14. Average nuclear DNA content (2C; pg) in Fucus vesiculosus (Fv, black circles), F. spiralis (Fs, grey circles) and small salt marsh Fucus (ssmF, white circles). Data from Illaunnginga (Locality 1), Clifden (Locality 2) and Achill Sound (Locality 3) are shown, together with unpublished data from Norway (**) and earlier published data (*) from Spain (Gómez Garreta et al., 2010), USA (Kapraun, 2005) and France (Phillips et al., 2011, recalculation from Peters et al., 2004).

Gómez Garreta, A., Ribera Siguan, M.A., Salvador Soler, N., Rull Lluch, J. & Kapraun, D.F. (2010). Fucales (Phaeophyceae) from Spain characterized by large-scale discontinuous nuclear DNA contents consistent with ancestral cryptopolyploidy. Phycologia, 49: 64–72.

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