The European election campaign did not really take off in Scotland.

The independence referendum has dominated debate. Even when the EU poll was mentioned, it was frequently in the context of predicting its impact on the outcome of September's vote.

One of the inferences which can be drawn, therefore, is that Ukip's success in winning one of Scotland's six seats at the European Parliament was not due to nuanced consideration of the issues. It is reasonable to assume that many of the Scottish voters who came out to vote for Nigel Farage's party did not do so because of a careful consideration of the relative merits of the parties' European manifestoes.

That is not to diminish the effectiveness of Ukip's top-line messages. For around one in ten Scots who voted, concern about immigration, particularly the impact on jobs, and a "plague-on-all-your-houses" rejection of the mainstream parties led them to put their cross in the box of the newcomer at the political table.

The fact that the proportion of the vote picked up by the party was much smaller in Scotland than in other parts of the UK should be of little comfort to the party's critics. The result has implications for all of Ukip's rivals.

It raises particular questions for Alex Salmond. The SNP leader made great play in the election campaign of calling on Scots voters to reject the nasty intolerance of Ukip. The election of David Coburn as Scotland's sixth MEP and Ukip's first in Scotland suggests the strategy failed.

This makes it harder for the SNP and the Yes campaign to use the differing political cultures north and south of the Border to bolster the case for independence.

In truth, the culture is not as different as some would like to argue. Fear of migrants, concerns about integration and assimilation, and worries about a shortage of jobs are evident in Scotland. Much of this is predicated on fear of the unknown. It is wrong to castigate immigrants for failing to integrate if little effort is made at community level to make them feel welcome.

However, there is a serious challenge here for Mr Salmond. Research revealed in The Herald last week showed significant support among Scots voters for several of Ukip's policies on immigration benefits. Such backing was perhaps surprisingly high among SNP supporters.

As a new report shows diversity is increasing across Scotland as immigrants settle into new areas, the Euro poll results might challenge the perception that most people are content with this development.

Many of the policies in the Scottish Government's White Paper on independence are predicated on increasing immigration, to generate growth and offset the demographic deficit of Scotland's ageing population.

The UK Treasury believes an extra half a million migrants will be need to achieve this. The First Minister's policy is predicated on much more immigration, but do SNP supporters agree?

Ukip's breakthrough is also a major headache for the Better Together campaign. Mr Farage has said having a Scottish MEP would give the party a voice in the independence debate. Will Ukip now demand a presence on referendum hustings? Better Together insists it will not be invited or allowed to join the pro-Union campaign but some voters will want to hear the party's voice.

Care must be taken not to draw too many conclusions when nearly two-thirds of the electorate stayed at home. Scotland remains broadly a welcoming and tolerant nation and Ukip's policies are populist but divisive. But dismissing Ukip as a fringe party north or south of the Border has not worked. The mainstream parties must do much more to challenge the fears and prejudices of those who support it and address their concerns in a positive way.